gcc: enable threads for uClinux

toolchain/gcc/patches/5.4.0/uclinux-threads.patch

@@ -0,0 +1,13 @@
+diff -Nur gcc-5.4.0.orig/gcc/config.gcc gcc-5.4.0/gcc/config.gcc
+--- gcc-5.4.0.orig/gcc/config.gcc	2015-09-10 16:17:53.000000000 +0200
++++ gcc-5.4.0/gcc/config.gcc	2016-06-16 21:41:39.526975484 +0200
+@@ -808,6 +808,9 @@
+ *-*-uclinux*)
+   extra_options="$extra_options gnu-user.opt"
+   use_gcc_stdint=wrap
++  case ${enable_threads} in
++    "" | yes | posix) thread_file='posix' ;;
++  esac
+   tm_defines="$tm_defines DEFAULT_LIBC=LIBC_UCLIBC SINGLE_LIBC"
+   ;;
+ *-*-rdos*)