Disable parallel build of mingw-w64-crt.

Unfortunately, parallel build issue is not yet fixed in current
mingw-w64 sources.

Signed-off-by: Alexey Neyman <stilor@att.net>

scripts/build/libc/mingw.sh

@@ -104,8 +104,11 @@ do_libc() {
         --build=${CT_BUILD}                                                           \
         --host=${CT_TARGET}                                                           \
 
+    # mingw-w64-crt has a missing dependency occasionally breaking the
+    # parallel build. See https://github.com/crosstool-ng/crosstool-ng/issues/246
+    # Do not pass ${JOBSFLAGS} - build serially.
     CT_DoLog EXTRA "Building mingw-w64-crt"
-    CT_DoExecLog ALL make ${JOBSFLAGS}
+    CT_DoExecLog ALL make
 
     CT_DoLog EXTRA "Installing mingw-w64-crt"
     CT_DoExecLog ALL make install DESTDIR=${CT_SYSROOT_DIR}