New USE() macros

For each CONFIG_SYMBOL, include/bb_config.h now has both ENABLE_SYMBOL
and USE_SYMBOL(x).  ENABLE_SYMBOL is still always defined (1 or 0) so that
if(ENABLE) should optimize out when it's zero.  The USE_SYMBOL(X) will only
splice in X if the symbol is defined, otherwise it'll be empty.

Thus we can convert this:

#ifdef CONFIG_ARGS
    opt = bb_getopt_ulflags(argc, argv, "ab:c"
#ifdef CONFIG_THINGY
        "d:"
#endif
        , &bvalue
#ifdef CONFIG_THINGY
        , &thingy
#endif
    );
#endif

into this:
    if (ENABLE_ARGS) {
        opt = bb_getopt_ulflags(argc, argv, "ab:c" USE_THINGY("d:"), &bvalue
                USE_THINGY(, &thingy));
    }

And it should produce the same code.

Unlike the old versions in include/_usage.h, the new USE_SYMBOL(x) can handle
commas in its arguments (as shown above).  (The _usage.h file is obsolete and
no longer generated.)

Nobody should need to include config.h directly anymore, bb_config.h should
define all the configuration stuff we need.  Someday, the CONFIG_SYMBOL
versions should go away in favor of ENABLE_SYMBOL and USE_SYMBOL().

Thanks to vodz for the new version of bb_mkdep.c that works with function
macros.

Makefile

@@ -185,7 +185,6 @@ randconfig: scripts/config/conf
 allyesconfig: scripts/config/conf
 	@./scripts/config/conf -y $(CONFIG_CONFIG_IN)
 	sed -i -r -e "s/^(USING_CROSS_COMPILER)=.*/# \1 is not set/" .config
-	echo "CONFIG_FEATURE_SHARED_BUSYBOX=y" >> .config
 	@./scripts/config/conf -o $(CONFIG_CONFIG_IN)
 
 allnoconfig: scripts/config/conf
@@ -197,7 +196,7 @@ allnoconfig: scripts/config/conf
 
 defconfig: scripts/config/conf
 	@./scripts/config/conf -y $(CONFIG_CONFIG_IN)
-	sed -i -r -e "s/^(USING_CROSS_COMPILER|CONFIG_(DEBUG.*|STATIC|SELINUX|BUILD_(AT_ONCE|LIBBUSYBOX)|FEATURE_(DEVFS|FULL_LIBBUSYBOX|SHARED_BUSYBOX|MTAB_SUPPORT|CLEAN_UP)))=.*/# \1 is not set/" .config
+	sed -i -r -e "s/^(USING_CROSS_COMPILER|CONFIG_(DEBUG.*|STATIC|SELINUX|BUILD_(AT_ONCE|LIBBUSYBOX)|FEATURE_(DEVFS|FULL_LIBBUSYBOX|SHARED_BUSYBOX|MTAB_SUPPORT|CLEAN_UP|UDHCP_DEBUG)))=.*/# \1 is not set/" .config
 	@./scripts/config/conf -o $(CONFIG_CONFIG_IN)
 
 
@@ -387,7 +386,7 @@ docs/busybox.net/BusyBox.html: docs/busybox.pod
 scripts/bb_mkdep: $(top_srcdir)/scripts/bb_mkdep.c
 	$(HOSTCC) $(HOSTCFLAGS) -o $@ $<
 
-DEP_INCLUDES := include/config.h include/bb_config.h include/_usage.h
+DEP_INCLUDES := include/config.h include/bb_config.h
 
 ifeq ($(strip $(CONFIG_BBCONFIG)),y)
 DEP_INCLUDES += include/bbconfigopts.h
@@ -414,21 +413,13 @@ include/config.h: .config
 
 include/bb_config.h: include/config.h
 	@echo -e "#ifndef BB_CONFIG_H\n#define BB_CONFIG_H" > $@
-	@sed -e 's/#undef CONFIG_\(.*\)/#define ENABLE_\1 0/' \
+	@sed -e h -e 's/#undef CONFIG_\(.*\)/#define ENABLE_\1 0/p' -e g \
-	    -e 's/#define CONFIG_\(.*\)/#define CONFIG_\1\n#define ENABLE_\1/' \
+	   -e 's/#undef CONFIG_\(.*\)/#define USE_\1(...)/p' -e g \
-		< $< >> $@
+	   -e 's/#define CONFIG_\([^ ]*\).*/#define ENABLE_\1 1/p' -e g -e \
+	   's/#define CONFIG_\([^ ]*\).*/#define USE_\1(...) __VA_ARGS__/p' \
+	   -e g $< >> $@
 	@echo "#endif" >> $@
 
-# Create macros for usage.h, e.g.:
-#if ENABLE_HAVE_DOT_CONFIG
-#define USAGE_HAVE_DOT_CONFIG(a) a
-#else
-#define USAGE_HAVE_DOT_CONFIG(a)
-#endif
-include/_usage.h: .config
-	$(disp_gen)
-	$(Q)awk '/CONFIG|BB_APPLET/{gsub("#[[:space:]]*|=y|.*CONFIG_|.*BB_APPLET_","");if(!/=/){print("#if ENABLE_"$$1"\n#define USAGE_"$$1"(a) a\n#else\n#define USAGE_"$$1"(a)\n#endif");}}' $(<) > $(@)
-
 clean:
 	- $(MAKE) -C scripts/config $@
 	- $(RM_F) docs/busybox.dvi docs/busybox.ps \

include/platform.h

@@ -78,9 +78,4 @@
 # endif
 #endif
 
-
-/* include USAGE_APPLET_x helper macros for usage.h.  */
-/*
-#include "_usage.h"
-*/
 #endif	/* platform.h	*/