adjust optional suite load order

mx.fastr/mx_fastr.py

@@ -385,8 +385,7 @@ def load_optional_suite(name):
     return opt_suite
 
 def mx_post_parse_cmd_line(opts):
-    # load optional suites
-    load_optional_suite('r_benchmarks')
+    # load optional suites, r_apptests first so r_benchmarks can find it
     global _apptests_suite
     _apptests_suite = load_optional_suite('r_apptests')
     if _apptests_suite:
@@ -397,6 +396,8 @@ def mx_post_parse_cmd_line(opts):
         suiteModel = "--src-suitemodel:" + ("sibling" if mx._src_suitemodel.nestedsuites_dirname() is None else "nested")
         os.environ['MX_SUITEMODEL'] = suiteModel
 
+    load_optional_suite('r_benchmarks')
+
 def mx_init(suite):
     global _fastr_suite
     _fastr_suite = suite