cbfstool: Clean up in preparation for adding new files

This enables more warnings on the cbfstool codebase and fixes the
issues that surface as a result. A memory leak that used to occur
when compressing files with lzma is also found and fixed.
Finally, there are several fixes for the Makefile:
 - Its autodependencies used to be broken because the target for
   the .dependencies file was misnamed; this meant that Make
   didn't know how to rebuild the file, and so would silently
   skip the step of updating it before including it.
 - The ability to build to a custom output directory by defining
   the obj variable had bitrotted.
 - The default value of the obj variable was causing implicit
   rules not to apply when specifying a file as a target without
   providing a custom value for obj.
 - Add a distclean target for removing the .dependencies file.

BUG=chromium:461875
TEST=Build an image with cbfstool both before and after.
BRANCH=None

Change-Id: I951919d63443f2b053c2e67c1ac9872abc0a43ca
Signed-off-by: Sol Boucher <solb@chromium.org>
Original-Commit-Id: 49293443b4e565ca48d284e9a66f80c9c213975d
Original-Change-Id: Ia7350c2c3306905984cfa711d5fc4631f0b43d5b
Original-Signed-off-by: Sol Boucher <solb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/257340
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Reviewed-on: http://review.coreboot.org/9937
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/util/cbfstool/Makefile.inc b/util/cbfstool/Makefile.inc
index 410d96c..a846e99 100644
--- a/util/cbfstool/Makefile.inc
+++ b/util/cbfstool/Makefile.inc
@@ -17,32 +17,42 @@
 cbfsobj += linux_trampoline.o
 cbfsobj += cbfs-payload-linux.o
 
+rmodobj :=
 rmodobj += rmodtool.o
 rmodobj += rmodule.o
 rmodobj += common.o
 rmodobj += elfheaders.o
 rmodobj += xdr.o
 
+TOOLCFLAGS ?= -std=c99 -Werror -Wall -Wextra
+TOOLCFLAGS += -Wcast-qual -Wmissing-prototypes -Wredundant-decls -Wshadow
+TOOLCFLAGS += -Wstrict-prototypes -Wwrite-strings
+TOOLCPPFLAGS ?= -D_POSIX_C_SOURCE=200809L # strdup() from string.h
+TOOLLINKFLAGS ?=
+
 ifeq ($(shell uname -s | cut -c-7 2>/dev/null), MINGW32)
 TOOLFLAGS+=-mno-ms-bitfields
 endif
 
 $(objutil)/cbfstool/%.o: $(top)/util/cbfstool/%.c
 	printf "    HOSTCC     $(subst $(objutil)/,,$(@))\n"
-	$(HOSTCC) $(TOOLFLAGS) $(HOSTCFLAGS) -c -o $@ $<
+	$(HOSTCC) $(TOOLCPPFLAGS) $(TOOLCFLAGS) $(HOSTCFLAGS) -c -o $@ $<
 
 $(objutil)/cbfstool/%.o: $(top)/util/cbfstool/lzma/%.c
 	printf "    HOSTCC     $(subst $(objutil)/,,$(@))\n"
-	$(HOSTCC) $(TOOLFLAGS) $(HOSTCFLAGS) -c -o $@ $<
+	$(HOSTCC) $(TOOLCPPFLAGS) $(TOOLCFLAGS) $(HOSTCFLAGS) -c -o $@ $<
 
 $(objutil)/cbfstool/%.o: $(top)/util/cbfstool/lzma/C/%.c
 	printf "    HOSTCC     $(subst $(objutil)/,,$(@))\n"
-	$(HOSTCC) $(TOOLFLAGS) $(HOSTCFLAGS) -c -o $@ $<
+	$(HOSTCC) $(TOOLCPPFLAGS) $(TOOLCFLAGS) $(HOSTCFLAGS) -c -o $@ $<
 
 $(objutil)/cbfstool/cbfstool: $(addprefix $(objutil)/cbfstool/,$(cbfsobj))
 	printf "    HOSTCC     $(subst $(objutil)/,,$(@)) (link)\n"
-	$(HOSTCC) $(TOOLFLAGS) -o $@ $(addprefix $(objutil)/cbfstool/,$(cbfsobj))
+	$(HOSTCC) $(TOOLLINKFLAGS) -o $@ $(addprefix $(objutil)/cbfstool/,$(cbfsobj))
 
 $(objutil)/cbfstool/rmodtool: $(addprefix $(objutil)/cbfstool/,$(rmodobj))
 	printf "    HOSTCC     $(subst $(objutil)/,,$(@)) (link)\n"
-	$(HOSTCC) $(TOOLFLAGS) -o $@ $(addprefix $(objutil)/cbfstool/,$(rmodobj))
+	$(HOSTCC) $(TOOLLINKFLAGS) -o $@ $(addprefix $(objutil)/cbfstool/,$(rmodobj))
+
+# Tolerate lzma sdk warnings
+$(objutil)/cbfstool/LzmaEnc.o: TOOLCFLAGS += -Wno-sign-compare -Wno-cast-qual