pcg-c fails to build unless 128-bit ops are supported (as e.g. on NetBSD/powerpc)

[he32]

This popped up on my radar due to a build failure on NetBSD/powerpc. This platform does not have native support for 128-bit integer operations.

gcc -O2 -D_FORTIFY_SOURCE=2 -O3 -std=c99 -I../include  -c -o pcg-global-32.o pcg-global-32.c
In file included from pcg-global-32.c:33:
../include/pcg_variants.h:2178:33: error: 'PCG_STATE_SETSEQ_64_INITIALIZER' undeclared here (not in a function)
 2178 | #define PCG32_INITIALIZER       PCG_STATE_SETSEQ_64_INITIALIZER
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pcg-global-32.c:35:38: note: in expansion of macro 'PCG32_INITIALIZER'
   35 | static pcg32_random_t pcg32_global = PCG32_INITIALIZER;
      |                                      ^~~~~~~~~~~~~~~~~
gmake[1]: *** [<builtin>: pcg-global-32.o] Error 1

Inspecting include/pcg_variants.h reveals that PCG_HAS_128BIT_OPS ends up as undefined on this platform, due to lack of __SIZEOF_INT128__ being defined, and hence PCG_STATE_SETSEQ_64_INITIALIZER also ends up being undefined, as it's only defined if PCG_HAS_128BIT_OPS is defined.