crt: Move the strtof() function from libmingwex.a to libmsvcr*.a

This avoids using this function (where strtof() is implemented
with strtof()) in UCRT builds.

In stdlib.h, we don't define __USE_MINGW_STRTOX when targeting
UCRT - with the intent that we'd use the CRT's implementation
instead. This makes that actually work as intended for strtof.

This also fixes accuracy issues reported in
https://github.com/msys2/MINGW-packages/issues/12472 by simply
deferring to the UCRT's implementation - as originally intended.

Signed-off-by: Martin Storsjö <martin@martin.st>

mingw-w64-crt/Makefile.am

diff --git a/mingw-w64-crt/Makefile.am b/mingw-w64-crt/Makefile.am
index 8026571..23b1ab9 100644
--- a/mingw-w64-crt/Makefile.am
+++ b/mingw-w64-crt/Makefile.am
@@ -181,6 +181,7 @@
   stdio/_putc_nolock.c \
   stdio/_putwc_nolock.c \
   stdio/acrt_iob_func.c \
+  stdio/strtof.c \
   stdio/snprintf_alias.c \
   stdio/vsnprintf_alias.c \
   math/frexp.c
@@ -576,7 +577,7 @@
   stdio/mingw_snprintfw.c  stdio/mingw_sprintf.c     stdio/mingw_sprintfw.c   stdio/mingw_sscanf.c      stdio/mingw_swscanf.c   \
   stdio/mingw_vfprintf.c   stdio/mingw_vfprintfw.c   stdio/mingw_vfscanf.c    stdio/mingw_vprintf.c     stdio/mingw_vprintfw.c  \
   stdio/mingw_vsnprintf.c  stdio/mingw_vsnprintfw.c  stdio/mingw_vsprintf.c   stdio/mingw_vsprintfw.c   stdio/mingw_wscanf.c    \
-  stdio/mingw_wvfscanf.c   stdio/snprintf.c          stdio/snwprintf.c        stdio/strtof.c            stdio/truncate.c        \
+  stdio/mingw_wvfscanf.c   stdio/snprintf.c          stdio/snwprintf.c        stdio/truncate.c        \
   stdio/ulltoa.c           stdio/ulltow.c            stdio/vasprintf.c        stdio/vfscanf.c           stdio/vfwscanf.c        \
   stdio/vscanf.c           stdio/vsnprintf.c         stdio/vsnwprintf.c        stdio/vsscanf.c         \
   stdio/vswscanf.c         stdio/vwscanf.c           stdio/wtoll.c            stdio/mingw_asprintf.c    stdio/mingw_vasprintf.c