ipq807x: backport kbuild fix to avoid spurious rebuilds

Signed-off-by: Felix Fietkau <nbd@nbd.name>

feeds/ipq807x/ipq807x/patches/001-backport_kbuild_fix.patch

@@ -0,0 +1,25 @@
+--- a/scripts/Makefile.lib
++++ b/scripts/Makefile.lib
+@@ -96,10 +96,10 @@ obj-dirs	:= $(addprefix $(obj)/,$(obj-di
+ # Note: Files that end up in two or more modules are compiled without the
+ #       KBUILD_MODNAME definition. The reason is that any made-up name would
+ #       differ in different configs.
+-name-fix = $(subst $(comma),_,$(subst -,_,$1))
+-basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))"
++name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote)
++basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))
+ modname_flags  = $(if $(filter 1,$(words $(modname))),\
+-                 -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
++                 -DKBUILD_MODNAME=$(call name-fix,$(modname)))
+ 
+ orig_c_flags   = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(KBUILD_SUBDIR_CCFLAGS) \
+                  $(ccflags-y) $(CFLAGS_$(basetarget).o)
+@@ -155,7 +155,7 @@ endif
+ 
+ c_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
+ 		 $(__c_flags) $(modkern_cflags)                           \
+-		 -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags)
++		 $(basename_flags) $(modname_flags)
+ 
+ a_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE)     \
+ 		 $(__a_flags) $(modkern_aflags)