[build] Disable ccache for all relevant build targets

The build process currently attempts to disable ccache for files using
the .incbin directive, but the rule fails to apply to anything beyond
the simple object target.  Fix by applying to all relevant build
targets (including debug objects, assembly listings, and so on).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/Makefile.housekeeping

 # Unfortunately ccache does not detect this dependency and caches
 # builds even when the binary file has changed.
 #
-$(BIN)/embedded.o : override CC := env CCACHE_DISABLE=1 $(CC)
-
-$(BIN)/clientcert.o : override CC := env CCACHE_DISABLE=1 $(CC)
+$(BIN)/embedded.% : override CC := env CCACHE_DISABLE=1 $(CC)
+$(BIN)/clientcert.% : override CC := env CCACHE_DISABLE=1 $(CC)
 
 # Version number
 #
 		  -DVERSION="\"$(VERSION)\""
 # Make sure the version number gets updated on every git checkout
 ifneq ($(GITVERSION),)
-$(BIN)/version.o : ../.git/index
+$(BIN)/version.% : ../.git/index
 endif
 
 # We automatically generate rules for any file mentioned in AUTO_SRCS