strerror_r-posix: Another fix, for HAVE_DECL_STRERROR_R on mingw
Commit
5ddd9d7 improved strerror_r on glibc systems (where
STRERROR_R_CHAR_P was defined twice with different values), but
missed mingw systems (where HAVE_DECL_STRERROR_R is now defined
twice with different values). Avoid the AC_CHECK_DECLS[_ONCE]
and AC_CHECK_FUNCS[_ONCE] m4 macros that call AC_DEFINE under the
hood, and instead limit our checks to just setting shell witnesses,
so that compilation on mingw doesn't trigger warnings (and mess up
subsequent tests that use -Werror) about a redefined C preprocessor
macro.
* m4/strerror_r.m4 (gl_FUNC_STRERROR_R, gl_FUNC_STRERROR_R_WORKS):
Avoid calling macros that may supply a conflicting AC_DEFINE().
Signed-off-by: Eric Blake <eblake@redhat.com>