Make mercury_event_scanner.h a static file.

trace/Mmakefile:
trace/mercury_event_scanner.h:
trace/.gitignore:
    Add mercury_event_scanner.h as a static file, no need to generate it.

trace/.gitignore

@@ -14,5 +14,4 @@ mercury_event_parser.c
 mercury_event_parser.h
 mercury_event_parser.output
 mercury_event_scanner.c
-mercury_event_scanner.h
 tags

trace/Mmakefile

@@ -78,6 +78,7 @@ HAND_TRACE_SRCS	=	\
 # The list of human-written C header files of the eventspec library.
 # Keep this list in alphabetical order, please.
 HAND_EVENTSPEC_HDRS	=	\
+			mercury_event_scanner.h	\
 			mercury_event_spec.h
 
 # The list of human-written C source files of the eventspec library.
@@ -88,8 +89,7 @@ HAND_EVENTSPEC_SRCS	=	\
 # The list of automatically created C header files.
 # Keep this list in alphabetical order, please.
 GEN_EVENTSPEC_HDRS	=	\
-			mercury_event_parser.h \
-			mercury_event_scanner.h
+			mercury_event_parser.h
 
 # The list of automatically created C source files.
 # Keep this list in alphabetical order, please.
@@ -246,10 +246,6 @@ mercury_event_scanner.c: mercury_event_scanner.l mercury_event_parser.h
 		-omercury_event_scanner.c \
 		mercury_event_scanner.l
 
-# XXX does mercury_event_scanner.h need to be generated at all?
-mercury_event_scanner.h: mercury_event_scanner.c
-	echo "extern int mercury_event_lex(void);" > mercury_event_scanner.h
-
 RPATH_1=$(SHLIB_RPATH_OPT)$(FINAL_INSTALL_MERC_LIB_DIR)
 RPATH_2=$(SHLIB_RPATH_SEP)$(FINAL_INSTALL_MERC_GC_LIB_DIR)
 

trace/mercury_event_scanner.h

@@ -0,0 +1,11 @@
+// vim: ts=4 sw=4 expandtab ft=c
+
+// Copyright (C) 2019 The Mercury team.
+// This file is distributed under the terms specified in COPYING.LIB.
+
+#ifndef MERCURY_EVENT_SCANNER_H
+#define MERCURY_EVENT_SCANNER_H
+
+extern int mercury_event_lex(void);
+
+#endif	// MERCURY_EVENT_SCANNER_H