Correct test finding behavior

Scan resources ignores the build dir so we can't set it to something
dumb like the directory we want to scan

tools/test_api.py

@@ -2077,9 +2077,8 @@ def find_tests(base_dir, target_name, toolchain_name, app_config=None):
     commons = []
 
     # Prepare the toolchain
-    toolchain = prepare_toolchain(
-        [base_dir], base_dir, target_name, toolchain_name, silent=True,
-        app_config=app_config)
+    toolchain = prepare_toolchain([base_dir], None, target_name, toolchain_name,
+                                  silent=True, app_config=app_config)
 
     # Scan the directory for paths to probe for 'TESTS' folders
     base_resources = scan_resources([base_dir], toolchain)

tools/toolchains/arm.py

@@ -360,7 +360,8 @@ class ARMC6(ARM_STD):
             self.flags['common'].append("-mcmse")
 
         # Create Secure library
-        if target.core == "Cortex-M23" or self.target.core == "Cortex-M33":
+        if ((target.core == "Cortex-M23" or self.target.core == "Cortex-M33") and
+            kwargs.get('build_dir', False)):
             build_dir = kwargs['build_dir']
             secure_file = join(build_dir, "cmse_lib.o")
             self.flags["ld"] += ["--import_cmse_lib_out=%s" % secure_file]