kbuild: fix ia64 breakage after introducing make -rR

kbuild used $¤(*F to get filename of target without extension.
This was used in several places all over kbuild, but introducing
make -rR broke his for all cases where we specified full path to
target/prerequsite. It is assumed that make -rR disables old style
suffix-rules which is why is suddenly failed.

ia64 was impacted by this change because several div* routines in
arch/ia64/lib are build using explicit paths and then kbuild failed.

Thanks to David Mosberger-Tang <David.Mosberger@acm.org> for an explanation
what was the root-cause and for testing on ia64.

This patch also fixes two uses of $(*F) in arch/um

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/Makefile.lib

@@ -82,12 +82,12 @@ obj-dirs	:= $(addprefix $(obj)/,$(obj-dirs))
 #       than one module. In that case KBUILD_MODNAME will be set to foo_bar,
 #       where foo and bar are the name of the modules.
 name-fix = $(subst $(comma),_,$(subst -,_,$1))
-basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(*F)))"
+basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))"
 modname_flags  = $(if $(filter 1,$(words $(modname))),\
                  -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
 
-_c_flags       = $(CFLAGS) $(EXTRA_CFLAGS) $(CFLAGS_$(*F).o)
-_a_flags       = $(AFLAGS) $(EXTRA_AFLAGS) $(AFLAGS_$(*F).o)
+_c_flags       = $(CFLAGS) $(EXTRA_CFLAGS) $(CFLAGS_$(basetarget).o)
+_a_flags       = $(AFLAGS) $(EXTRA_AFLAGS) $(AFLAGS_$(basetarget).o)
 _cpp_flags     = $(CPPFLAGS) $(EXTRA_CPPFLAGS) $(CPPFLAGS_$(@F))
 
 # If building the kernel in a separate objtree expand all occurrences