Set the executable installation directory using --bindir.

Support setting an alternative executable installation directory using the
configure script's --bindir option.

Patch contributed by Keri Harris.

scripts/Mmake.vars.in:
scripts/mdprof.in:
scripts/mmc.in:
scripts/mprof.in:
    As above.

scripts/Mmake.vars.in

@@ -641,10 +641,11 @@ endif
 # Handle some autoconf weirdness, it relies on these variables but doesn't
 # define them.
 prefix=@prefix@
+exec_prefix=@exec_prefix@
 PACKAGE=mercury-$(VERSION)
 
 INSTALL_PREFIX		= $(DESTDIR_AND_SLASH)@prefix@
-INSTALL_BINDIR		= $(INSTALL_PREFIX)/bin
+INSTALL_BINDIR		= $(DESTDIR_AND_SLASH)@bindir@
 INSTALL_LIBDIR		= $(INSTALL_PREFIX)/lib/mercury
 INSTALL_INFO_DIR	= $(DESTDIR_AND_SLASH)@infodir@
 INSTALL_DVI_DIR		= $(DESTDIR_AND_SLASH)@docdir@
@@ -658,7 +659,7 @@ INSTALL_ELISP_DIR	= $(INSTALL_PREFIX)/lib/mercury/elisp
 INSTALL_CGI_DIR		= $(DESTDIR_AND_SLASH)@CGIDIR@
 
 FINAL_INSTALL_PREFIX	= @prefix@
-FINAL_INSTALL_BINDIR 	= $(FINAL_INSTALL_PREFIX)/bin
+FINAL_INSTALL_BINDIR 	= @bindir@
 FINAL_INSTALL_LIBDIR	= $(FINAL_INSTALL_PREFIX)/lib/mercury
 FINAL_INSTALL_INFO_DIR	= @infodir@
 FINAL_INSTALL_MAN_DIR	= @mandir@
@@ -675,7 +676,7 @@ INSTALL_GRADE_INT_DIR	= $(INSTALL_LIBDIR)/ints/$(GRADESTRING)
 INSTALL_INC_DIR		= $(INSTALL_LIBDIR)/inc
 INSTALL_MMAKE_DIR	= $(INSTALL_LIBDIR)/mmake
 FULLARCH		= @FULLARCH@
-INSTALL_MERC_BIN_DIR	= $(INSTALL_PREFIX)/bin
+INSTALL_MERC_BIN_DIR	= $(INSTALL_BINDIR)
 INSTALL_MERC_GRADELESS_LIB_DIR = $(INSTALL_LIBDIR)/lib
 FINAL_INSTALL_MERC_GRADELESS_LIB_DIR = $(FINAL_INSTALL_LIBDIR)/lib
 INSTALL_MERC_LIB_DIR	= $(INSTALL_LIBDIR)/lib/$(GRADESTRING)

scripts/mdprof.in

@@ -15,7 +15,9 @@
 # unprocessed, which is what we want; the web servers breaks up QUERY_STRING
 # on boundaries inappropriate for us when computing the command line arguments.
 
-PATH=@prefix@/bin:$PATH
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+PATH=@bindir@:$PATH
 export PATH
 
 # Use less heap at the expense of increased time spent in the GC.

scripts/mmc.in

@@ -14,7 +14,9 @@
 # MERCURY_COMPILER, MERCURY_C_COMPILER, MERCURY_DEFAULT_GRADE,
 # MERCURY_DEFAULT_OPT_LEVEL.
 
-MERCURY_COMPILER=${MERCURY_COMPILER-'@PREFIX@/bin/mercury_compile'}
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+MERCURY_COMPILER=${MERCURY_COMPILER-"@bindir@/mercury_compile"}
 MERCURY_CONFIG_DIR=${MERCURY_CONFIG_DIR-${MERCURY_STDLIB_DIR-'@CONFIG_LIBDIR@'}}
 export MERCURY_COMPILER MERCURY_CONFIG_DIR
 

scripts/mprof.in

@@ -12,7 +12,9 @@
 #
 # Environment variables: MERCURY_PROFILER.
 
-MPROF=${MERCURY_PROFILER="@PREFIX@/bin/mercury_profile"}
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+MPROF=${MERCURY_PROFILER="@bindir@/mercury_profile"}
 
 case $# in
 	0) exec $MPROF ;;