configure.ac: disable check sizeof pid_t for mingw

it's not correct to check for it in mingw

Author: naveen521kk

configure.ac

@@ -3336,10 +3336,17 @@ AC_CHECK_SIZEOF([double], [8])
 AC_CHECK_SIZEOF([fpos_t], [4])
 AC_CHECK_SIZEOF([size_t], [4])
 AC_CHECK_ALIGNOF([size_t])
-AC_CHECK_SIZEOF([pid_t], [4])
 AC_CHECK_SIZEOF([uintptr_t])
 AC_CHECK_ALIGNOF([max_align_t])
 
+case $host_os in
+  mingw*) ;;
+  *)
+    AC_CHECK_SIZEOF([pid_t], [4])
+    ;;
+esac
+
+
 AC_TYPE_LONG_DOUBLE
 AC_CHECK_SIZEOF([long double], [16])