Snippets for mpfr 4.2.2 from Alpine ppc64le

Sourced from https://build.alpinelinux.org/buildlogs/build-edge-ppc64le/main/mpfr4/mpfr4-4.2.2-r0.log.

• tsprintf.c:336:40: warning: '%s' directive writing up to 1 bytes into a region of size between 0 and 19 [-Wformat-overflow=]
    336 |                   sprintf (fmt, "%s%%%s%s%sR%s%c", expected, ps[fmtpsflags],
        |                                        ^~