strtold: New module. * lib/stdlib.in.h (strtold): New declaration. * lib/strtold.c: New file. * lib/strtod.c: Consider USE_LONG_DOUBLE. (STRTOD, LDEXP, HAVE_UNDERLYING_STRTOD, DOUBLE, MIN, MAX, L_, USE_LDEXP): New macros. (LDEXP, scale_radix_exp, parse_number, STRTOD): Adapt for USE_LONG_DOUBLE. (underlying_strtod): Remove function. Replace with some macros. Re-add the code for a missing underlying function that was removed on 2013-02-19. * m4/strtold.m4: New file. * m4/stdlib_h.m4 (gl_STDLIB_H): Test whether strtold is declared. (gl_STDLIB_H_DEFAULTS): Initialize GNULIB_STRTOLD, HAVE_STRTOLD, REPLACE_STRTOLD. * modules/stdlib (Makefile.am): Substitute GNULIB_STRTOLD, HAVE_STRTOLD, REPLACE_STRTOLD. * modules/strtold: New file. * doc/posix-functions/strtold.texi: Document the new module.

Files:
tests/test-memchr.c
tests/zerosize-ptr.h
tests/signature.h
tests/macros.h
m4/mmap-anon.m4

Depends-on:
extensions
getpagesize

configure.ac:
dnl Check for prerequisites for memory fence checks.
gl_FUNC_MMAP_ANON
AC_CHECK_HEADERS_ONCE([sys/mman.h])
AC_CHECK_FUNCS_ONCE([mprotect])

Makefile.am:
TESTS += test-memchr
check_PROGRAMS += test-memchr