devel/gcc: Check and build GNU sed if not available on build host

Closes #2300

bare/config/devel/gnu-default-tools.bset

@@ -6,6 +6,12 @@
 
 %define gcc_version_message RTEMS bare %{rtems_version}, RSB %{_sbgit_id}, Newlib %{newlib_version}
 
+#
+# GCC requires a GNU sed so build an internal version if one is not
+# available
+#
+%include textproc/gsed-internal
+
 #
 # Build gdb first to raise the Python install error as early as
 # possible. GDB needs expat so it needs to be built before gdb.