crt: Add emulation of _get_fmode() function for pre-msvcr80 import libs

Function _get_fmode() is available in msvcr80+, UCRT and also in
msvcrt.dll since Windows Vista.

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 a489470..16800eb 100644
--- a/mingw-w64-crt/Makefile.am
+++ b/mingw-w64-crt/Makefile.am
@@ -562,6 +562,7 @@
   misc/_free_locale.c \
   misc/_get_current_locale.c \
   misc/_get_doserrno.c \
+  misc/_get_fmode.c \
   misc/_initterm_e.c \
   misc/_set_doserrno.c \
   misc/_time64.c \
@@ -625,6 +626,7 @@
   misc/_free_locale.c \
   misc/_get_current_locale.c \
   misc/_get_doserrno.c \
+  misc/_get_fmode.c \
   misc/_initterm_e.c \
   misc/_set_doserrno.c \
   misc/output_format.c \
@@ -891,6 +893,7 @@
   misc/_get_doserrno.c \
   misc/_get_dstbias.c \
   misc/_get_errno.c \
+  misc/_get_fmode.c \
   misc/_get_pgmptr.c \
   misc/_get_timezone.c \
   misc/_get_tzname.c \

mingw-w64-crt/lib-common/msvcrt.def.in

diff --git a/mingw-w64-crt/lib-common/msvcrt.def.in b/mingw-w64-crt/lib-common/msvcrt.def.in
index ee7515c..1970da2 100644
--- a/mingw-w64-crt/lib-common/msvcrt.def.in
+++ b/mingw-w64-crt/lib-common/msvcrt.def.in
@@ -1429,7 +1429,7 @@
 _get_environ
 F_ARM_ANY(_get_errno) ; i386 and x64 _get_errno replaced by emu
 _get_fileinfo
-_get_fmode
+F_ARM_ANY(_get_fmode) ; i386 and x64 _get_fmode replaced by emu
 F_X86_ANY(_get_osplatform)
 F_X86_ANY(_get_osver)
 F_ARM_ANY(_get_output_format) ; i386 and x64 _get_output_format replaced by emu

mingw-w64-crt/misc/_get_fmode.c

diff --git a/mingw-w64-crt/misc/_get_fmode.c b/mingw-w64-crt/misc/_get_fmode.c
new file mode 100644
index 0000000..0aab079
--- /dev/null
+++ b/mingw-w64-crt/misc/_get_fmode.c
@@ -0,0 +1,20 @@
+/**
+ * This file has no copyright assigned and is placed in the Public Domain.
+ * This file is part of the mingw-w64 runtime package.
+ * No warranty is given; refer to the file DISCLAIMER.PD within this package.
+ */
+#include <stdlib.h>
+#include <errno.h>
+
+errno_t __cdecl _get_fmode(int *value)
+{
+  if (!value)
+  {
+    errno = EINVAL;
+    return EINVAL;
+  }
+
+  *value = _fmode;
+  return 0;
+}
+errno_t (__cdecl *__MINGW_IMP_SYMBOL(_get_fmode))(int *) = _get_fmode;