Makefile: learn to generate listings for targets requiring special flags

'make git.s' to debug code generation of main() fails because
git.c makes use of preprocessor symbols such as GIT_VERSION that
are not set.  make does not generate code listings for
builtin_help.c, exec_cmd.c, builtin-init-db.c, config.c, http.c,
or http-walker.c either, for the same reason.

So pass the flags used to generate each .o file when generating
the corresponding assembler listing.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -1468,15 +1468,15 @@ strip: $(PROGRAMS) git$X
 	$(STRIP) $(STRIP_OPTS) $(PROGRAMS) git$X
 
 git.o: common-cmds.h
-git.o: ALL_CFLAGS += -DGIT_VERSION='"$(GIT_VERSION)"' \
+git.s git.o: ALL_CFLAGS += -DGIT_VERSION='"$(GIT_VERSION)"' \
 	'-DGIT_HTML_PATH="$(htmldir_SQ)"'
 
 git$X: git.o $(BUILTIN_OBJS) $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ git.o \
 		$(BUILTIN_OBJS) $(ALL_LDFLAGS) $(LIBS)
 
 builtin-help.o: common-cmds.h
-builtin-help.o: ALL_CFLAGS += \
+builtin-help.s builtin-help.o: ALL_CFLAGS += \
 	'-DGIT_HTML_PATH="$(htmldir_SQ)"' \
 	'-DGIT_MAN_PATH="$(mandir_SQ)"' \
 	'-DGIT_INFO_PATH="$(infodir_SQ)"'
@@ -1637,21 +1637,21 @@ git.o git.spec \
 %.o: %.S GIT-CFLAGS
 	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) $<
 
-exec_cmd.o: ALL_CFLAGS += \
+exec_cmd.s exec_cmd.o: ALL_CFLAGS += \
 	'-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' \
 	'-DBINDIR="$(bindir_relative_SQ)"' \
 	'-DPREFIX="$(prefix_SQ)"'
 
-builtin-init-db.o: ALL_CFLAGS += \
+builtin-init-db.s builtin-init-db.o: ALL_CFLAGS += \
 	-DDEFAULT_GIT_TEMPLATE_DIR='"$(template_dir_SQ)"'
 
-config.o: ALL_CFLAGS += -DETC_GITCONFIG='"$(ETC_GITCONFIG_SQ)"'
+config.s config.o: ALL_CFLAGS += -DETC_GITCONFIG='"$(ETC_GITCONFIG_SQ)"'
 
-http.o: ALL_CFLAGS += -DGIT_USER_AGENT='"git/$(GIT_VERSION)"'
+http.s http.o: ALL_CFLAGS += -DGIT_USER_AGENT='"git/$(GIT_VERSION)"'
 
 ifdef NO_EXPAT
 http-walker.o: http.h
-http-walker.o: ALL_CFLAGS += -DNO_EXPAT
+http-walker.s http-walker.o: ALL_CFLAGS += -DNO_EXPAT
 endif
 
 git-%$X: %.o $(GITLIBS)