meson: also reject shifts that change the sign bit

meson: also reject shifts that change the sign bit

../src/test/test-sizeof.c: In function ‘main’:
../src/test/test-sizeof.c:70:24: error: result of ‘1 << 31’ requires 33 bits to represent, but ‘int’ only has 32 bits [-Werror=shift-overflow=]
                 X = (1 << 31),
                        ^~
cc1: some warnings being treated as errors

Follow-up for b05ecb8cadd8c32d31b1aabcff4e507bd89b5465.