Version check the compiler in all build functions

This enables the use of Mbed Studio's version of ARMC6.

Author: bridadan

tools/build_api.py

@@ -607,6 +607,7 @@ def build_library(src_paths, build_path, target, toolchain_name,
         src_paths, build_path, target, toolchain_name, macros=macros,
         clean=clean, jobs=jobs, notify=notify, app_config=app_config,
         build_profile=build_profile, ignore=ignore)
+    toolchain.version_check()
 
     # The first path will give the name to the library
     if name is None:
@@ -781,6 +782,7 @@ def build_lib(lib_id, target, toolchain_name, clean=False, macros=None,
             src_paths, tmp_path, target, toolchain_name, macros=macros,
             notify=notify, build_profile=build_profile, jobs=jobs, clean=clean,
             ignore=ignore)
+        toolchain.version_check()
 
         notify.info("Building library %s (%s, %s)" %
                     (name.upper(), target.name, toolchain_name))
@@ -925,6 +927,7 @@ def build_mbed_libs(target, toolchain_name, clean=False, macros=None,
         toolchain = prepare_toolchain(
             [""], tmp_path, target, toolchain_name, macros=macros, notify=notify,
             build_profile=build_profile, jobs=jobs, clean=clean, ignore=ignore)
+        toolchain.version_check()
 
         config = toolchain.config
         config.add_config_files([MBED_CONFIG_FILE])