bitcoin: remove i386 HAVE_BUILTIN_MUL_OVERFLOW workaround (#6140)
bitcoin: remove i386 HAVE_BUILTIN_MUL_OVERFLOW workaround (#6140)

This should no-longer be necessary now that
https://github.com/bitcoin/bitcoin/pull/21882 has been merged upstream.
googlefonts/oss-fuzz,googlefonts/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,googlefonts/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz