Include <fcntl.h> for the declaration of posix_fallocate.  This
avoids an implicit function declaration and build issues with future
compilers.

Submitted upstream: <https://midnight-commander.org/ticket/4438>

diff --git a/m4.include/mc-get-fs-info.m4 b/m4.include/mc-get-fs-info.m4
index 5afc9f1bb938bfcd..403045aadc810ba7 100644
--- a/m4.include/mc-get-fs-info.m4
+++ b/m4.include/mc-get-fs-info.m4
@@ -8,6 +8,7 @@ AC_DEFUN([gl_POSIX_FALLOCATE], [
     AC_LINK_IFELSE([AC_LANG_PROGRAM([[
         #define _XOPEN_SOURCE 600
         #include <stdlib.h>
+        #include <fcntl.h>
         #if defined(__GLIBC__) && (__GLIBC__ < 2 || __GLIBC_MINOR__ < 7)
             possibly broken posix_fallocate
         #endif