kbuild: remove cc-option test of -fno-strict-overflow

The minimal compiler versions, GCC 4.9 and Clang 10 support this flag.

Here is the godbolt:
https://godbolt.org/z/odq8h9Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: NNathan Chancellor <natechancellor@gmail.com>
Acked-by: NWill Deacon <will@kernel.org>

Makefile

@@ -928,7 +928,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
 KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
 
 # disable invalid "can't wrap" optimizations for signed / pointers
-KBUILD_CFLAGS	+= $(call cc-option,-fno-strict-overflow)
+KBUILD_CFLAGS	+= -fno-strict-overflow
 
 # clang sets -fmerge-all-constants by default as optimization, but this
 # is non-conforming behavior for C and in fact breaks the kernel, so we

arch/arm64/kernel/vdso32/Makefile

@@ -90,7 +90,7 @@ VDSO_CFLAGS  += -O2
 # Some useful compiler-dependent flags from top-level Makefile
 VDSO_CFLAGS += $(call cc32-option,-Wdeclaration-after-statement,)
 VDSO_CFLAGS += $(call cc32-option,-Wno-pointer-sign)
-VDSO_CFLAGS += $(call cc32-option,-fno-strict-overflow)
+VDSO_CFLAGS += -fno-strict-overflow
 VDSO_CFLAGS += $(call cc32-option,-Werror=strict-prototypes)
 VDSO_CFLAGS += $(call cc32-option,-Werror=date-time)
 VDSO_CFLAGS += $(call cc32-option,-Werror=incompatible-pointer-types)