MIPS: vdso: Define BUILD_VDSO32 when building a 32bit kernel

The confinement of the 32bit specific VDSO functions missed to define
BUILD_VDSO32 when building a 32bit MIPS kernel:

arch/mips/vdso/vgettimeofday.c: In function __vdso_clock_gettime:
arch/mips/vdso/vgettimeofday.c:17:9: error: implicit declaration of function __cvdso_clock_gettime32

arch/mips/vdso/vgettimeofday.c: In function __vdso_clock_getres:
arch/mips/vdso/vgettimeofday.c:39:9: error: implicit declaration of function __cvdso_clock_getres_time32

Force the define for 32bit builds in the VDSO Makefile.

Fixes: bf27984 ("lib/vdso: Build 32 bit specific functions in the right context")
Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Paul Burton <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: KAGA-KOKO

arch/mips/vdso/Makefile

@@ -18,6 +18,10 @@ ccflags-vdso := \
 	$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
 	-D__VDSO__
 
+ifndef CONFIG_64BIT
+ccflags-vdso += -DBUILD_VDSO32
+endif
+
 ifdef CONFIG_CC_IS_CLANG
 ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS))
 endif