Makefile: Improve generated_defconfig file handling

Commit 2027e99e61 ("Makefile: Run defconfig files through the C
preprocessor") adds `generated_defconfig' file, but fails to clean that
up. It might be useful to have that file around after `make' is done,
but it's better to clean that up on `make clean'. Also we probably want
to hide it in `git status' list. This patch makes the described changes,
and also adds `-P' parameter to the CPP command that produces the
`generated_defconfig' to avoid generating linemarkers.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Fixes: 2027e99e61 ("Makefile: Run defconfig files through the C preprocessor")
Acked-by: Andrew Davis <afd@ti.com>

.gitignore

@@ -63,6 +63,7 @@ fit-dtb.blob*
 /spl/
 /tpl/
 /defconfig
+/generated_defconfig
 
 #
 # Generated include files

Makefile

@@ -2233,6 +2233,7 @@ clean: $(clean-dirs)
 		-o -name modules.builtin -o -name '.tmp_*.o.*' \
 		-o -name 'dsdt_generated.aml' -o -name 'dsdt_generated.asl.tmp' \
 		-o -name 'dsdt_generated.c' \
+		-o -name 'generated_defconfig' \
 		-o -name '*.efi' -o -name '*.gcno' -o -name '*.so' \) \
 		-type f -print | xargs rm -f
 

scripts/kconfig/Makefile

@@ -93,7 +93,7 @@ endif
 endif
 
 %_defconfig: $(obj)/conf
-	$(Q)$(CPP) -nostdinc -I $(srctree) -undef -x assembler-with-cpp $(srctree)/arch/$(SRCARCH)/configs/$@ -o generated_defconfig
+	$(Q)$(CPP) -nostdinc -P -I $(srctree) -undef -x assembler-with-cpp $(srctree)/arch/$(SRCARCH)/configs/$@ -o generated_defconfig
 	$(Q)$< $(silent) --defconfig=generated_defconfig $(Kconfig)
 
 # Added for U-Boot (backward compatibility)