Add a %testing section to the configuration files.

source-builder/config/gcc-common-1.cfg

@@ -178,3 +178,7 @@ BuildRoot: %{_tmppath}/%{name}-root-%(%{__id_u} -n)
 
   # Don't want libffi's man-pages
   %{__rmfile} $SB_BUILD_ROOT%{_mandir}/man3/*ffi*
+
+%testing
+  # Add testing here.
+  export RUNTESTFLAGS=--target_board=%{_target}-run

source-builder/sb/config.py

@@ -197,6 +197,9 @@ class package:
     def include(self):
         return self.find_directive('%include')
 
+    def testing(self):
+        return self.find_directive('%testing')
+
     def long_name(self):
         return self.name()
 
@@ -209,7 +212,8 @@ class file:
                    '%clean',
                    '%install',
                    '%include',
-                   '%install' ]
+                   '%install',
+                   '%testing' ]
 
     _ignore = [ re.compile('%setup'),
                 re.compile('%configure'),