Fix bugs and nits pointed out by shellcheck.

scripts/mgnuc.in:
    Delete the unused variables AS, AS_OPTS, HLD_OPTS and ARG_OPTS.
    The first two are hstorical relics, HLD_OPTS lost its raison d'etre
    when we deleted the hl grades; I don't know what we used ARG_OPTS for.

    Make the unused variable CFLAGS_FOR_ANSI used.

    Fix a spelling inconsistency: DEBUG_OPT vs DEBUG_OPTS.

scripts/ml.in:
    Delete the unused variables NONSHARED_LIB_DIR and DL_LIBRARY.

scripts/parse_grade_options.sh-subr:
    Fix typos that prevented an almost-never-used option from working.

scripts/parse_ml_options.sh-subr.in:
    Fix a quoting error.

tools/bootcheck:
    Comment out the definition of an unused variable. (Its parallel
    exists and is used in c2init.in, which is why it is not deleted.)

    Fix typos in spelling SSDB_LIB_NAME.

    Quote a variable value that may contain spaces.

    Replace "cat file | cmd" with "cmd < file".

scripts/mgnuc.in

@@ -18,7 +18,6 @@
 # *************************************************************************
 
 FULLARCH=@FULLARCH@
-NONSHARED_LIB_DIR=${MERCURY_NONSHARED_LIB_DIR=@NONSHARED_LIB_DIR@}
 
 DEFAULT_GRADE=${MERCURY_DEFAULT_GRADE=@DEFAULT_GRADE@}
 CC=${MERCURY_C_COMPILER="@CC@"}
@@ -30,14 +29,13 @@ CFLAGS_FOR_LTO="@CFLAGS_FOR_LTO@"
 CFLAGS_FOR_NO_STRICT_ALIASING="@CFLAGS_FOR_NO_STRICT_ALIASING@"
 CFLAGS_FOR_ANSI="@CFLAGS_FOR_ANSI@"
 CFLAGS_FOR_SANITIZERS="@CFLAGS_FOR_SANITIZERS@"
-AS="@AS@"
 BYTES_PER_WORD="@BYTES_PER_WORD@"
 MKTEMP=@MKTEMP@
 TMPDIR=${TMPDIR=/tmp}
 
 case "${C_COMPILER_TYPE}" in
     gcc*)
-        ANSI_OPTS="@CFLAGS_FOR_ANSI@"
+        ANSI_OPTS="${CFLAGS_FOR_ANSI}"
         CHECK_OPTS="
             -Wall -Wwrite-strings
             -Wshadow -Wstrict-prototypes -Wmissing-prototypes -Wno-unused"
@@ -71,7 +69,7 @@ case "${C_COMPILER_TYPE}" in
               OPT_OPTS="-O2 ${CFLAGS_FOR_NO_STRICT_ALIASING} -fomit-frame-pointer"
               ;;
         esac
-        DEBUG_OPT="-g"
+        DEBUG_OPTS="-g"
         DISABLE_OPTS_OPT="-O0"
         COMPILER_HALT_AT_WARN_OPT="-Werror"
         COMPILER=gcc
@@ -80,7 +78,7 @@ case "${C_COMPILER_TYPE}" in
         ANSI_OPTS=
         CHECK_OPTS="-w"
         OPT_OPTS="@OPT_FLAGS_FOR_CLANG@ ${CFLAGS_FOR_NO_STRICT_ALIASING} -fomit-frame-pointer"
-        DEBUG_OPT="-g"
+        DEBUG_OPTS="-g"
         DISABLE_OPTS_OPT="-O0"
         COMPILER_HALT_AT_WARN_OPT="-Werror"
         COMPILER=clang
@@ -100,14 +98,13 @@ case "${C_COMPILER_TYPE}" in
         ANSI_OPTS=
         CHECK_OPTS=
         OPT_OPTS="-O"
-        DEBUG_OPT="-g"
+        DEBUG_OPTS="-g"
         DISABLE_OPTS_OPT="-O0"
         COMPILER_HALT_AT_WARN_OPT=""
         COMPILER=unknown
         ;;
 esac
 
-AS_OPTS=""
 SPLIT_OPTS=""
 INLINE_ALLOC_OPTS=""
 
@@ -255,7 +252,7 @@ ALL_LOCAL_C_INCL_DIRS=${MERCURY_ALL_LOCAL_C_INCL_DIRS=@ALL_LOCAL_C_INCL_DIRS@}
 # compiler/compile_target_code.m.
 
 case ${c_debug} in
-    true)       C_DEBUG_OPTS="${DEBUG_OPT}" ;;
+    true)       C_DEBUG_OPTS="${DEBUG_OPTS}" ;;
     false)      C_DEBUG_OPTS="" ;;
 esac
 
@@ -469,7 +466,7 @@ case ${ss_debug} in
 esac
 
 case ${ll_debug} in
-    true)           LL_DEBUG_OPTS="-DMR_LL_DEBUG ${DEBUG_OPT} ${DISABLE_OPTS_OPT}" ;;
+    true)           LL_DEBUG_OPTS="-DMR_LL_DEBUG ${DEBUG_OPTS} ${DISABLE_OPTS_OPT}" ;;
     false)          LL_DEBUG_OPTS="" ;;
 esac
 
@@ -701,7 +698,6 @@ ALL_CC_OPTS="${MERC_ALL_C_INCL_DIRS}\
     ${OPT_OPTS}\
     ${LTO_OPTS}\
     ${HLC_OPTS}\
-    ${HLD_OPTS}\
     ${GCC_OPTS}\
     ${HALT_AT_WARN_OPT}\
     ${MSVCRT_OPTS}\
@@ -731,7 +727,6 @@ ALL_CC_OPTS="${MERC_ALL_C_INCL_DIRS}\
     ${THREADSCOPE_OPTS}\
     ${REGION_OPTS}\
     ${ARCH_OPTS}\
-    ${ARG_OPTS}\
     ${FN_ALIGN_OPTS}\
     ${INVISIBLE_OPTS}"
 

scripts/ml.in

@@ -33,7 +33,6 @@ DEFAULT_GRADE=${MERCURY_DEFAULT_GRADE=@DEFAULT_GRADE@}
 
 # add /usr/local/lib to the default search path, if needed
 ALL_LOCAL_C_LIB_DIRS=${MERCURY_ALL_LOCAL_C_LIB_DIRS=@ALL_LOCAL_C_LIB_DIRS@}
-NONSHARED_LIB_DIR=${MERCURY_NONSHARED_LIB_DIR=@NONSHARED_LIB_DIR@}
 DEMANGLER=${MERCURY_DEMANGLER=mdemangle}
 CC=${MERCURY_C_COMPILER="@CC@"}
 C_COMPILER_TYPE=${MERCURY_C_COMPILER_TYPE="@C_COMPILER_TYPE@"}
@@ -74,11 +73,6 @@ SHARED_LIBS=${MERCURY_SHARED_LIBS="@SHARED_LIBS_SH@"}
 LINK=${LINK=/stack:10485760}   # 10 Mb
 export LINK
 
-# On some systems we need -ldl (libdl.so) for dlopen() etc.
-# The name of the needed library is determined by autoconf and passed through
-# this variable.
-DL_LIBRARY="@DL_LIBRARY@"
-
 # Likewise for -lreadline -l{termcap,curses,ncurses}
 READLINE_LIBRARIES="@READLINE_LIBRARIES@"
 

scripts/parse_grade_options.sh-subr

@@ -226,10 +226,10 @@
         ;;
 
     --low-level-debug)
-        ll_debug= true
+        ll_debug=true
         ;;
     --no-low-level-debug)
-        ll_debug= false
+        ll_debug=false
         ;;
 
     --extend-stacks-when-needed)

scripts/parse_ml_options.sh-subr.in

@@ -187,7 +187,7 @@ Initialization options:
 		Mercury runtime.  Flags can also be passed at runtime
 		in the MERCURY_OPTIONS environment variable.
 		For the list of available flags, see the documentation
-		for MERCURY_OPTIONS in the "Environment" chapter
+		for MERCURY_OPTIONS in the \"Environment\" chapter
 		of the Mercury User's Guide.
 	--experimental-complexity <filename>
 		Set up for the experimental determination of the complexity