Improvements to Sam's platform_init.c commit

Author: Bogdan Marinescu

libraries/mbed/targets/hal/TARGET_Freescale/TARGET_KLXX/TARGET_KL05Z/platform_init.c renamed to libraries/mbed/targets/hal/TARGET_Freescale/TARGET_KLXX/TARGET_KL05Z/mbed_overrides.c

@@ -181,23 +181,20 @@ def build_mbed_libs(target, toolchain_name, options=None, verbose=False, clean=F
     # Common Sources
     mbed_resources = toolchain.scan_resources(MBED_COMMON)
     objects += toolchain.compile_sources(mbed_resources, TMP_PATH, [MBED_LIBRARIES, BUILD_TARGET])
-    
-    # Keep retargeting as a standalone object to be sure the
-    # C standard library symbols get overridden
-    retargeting = None
+
+    # A number of compiled files need to be copied as objects as opposed to
+    # being part of the mbed library, for reasons that have to do with the way
+    # the linker search for symbols in archives. These are:
+    #   - retarget.o: to make sure that the C standard lib symbols get overridden
+    #   - board.o: mbed_die is weak
+    #   - mbed_overrides.o: this contains platform overrides of various weak SDK functions
+    separate_names, separate_objects = ['retarget.o', 'board.o', 'mbed_overrides.o'], []
     for o in objects:
-        if o.endswith('retarget.o'):
-            retargeting = o
-    objects.remove(retargeting)
-    # We need to have a file that overrides weak delcatations on a per board basis and the
-    #   lesser evil is to pull in this file if it extist rather than add board specific 
-    #   startup code in the /targets/cmsis directory
-    platform_initialize = None
-    for p in objects:
-        if p.endswith('platform_init.o'):
-            platform_initialize = p
-            objects.remove(platform_initialize)
+        for name in separate_names:
+            if o.endswith(name):
+                separate_objects.append(o)
+    for o in separate_objects:
+        objects.remove(o)
     toolchain.build_library(objects, BUILD_TOOLCHAIN, "mbed")
-    toolchain.copy_files(retargeting, BUILD_TOOLCHAIN)
-    toolchain.copy_files(platform_initialize, BUILD_TOOLCHAIN)
-
+    for o in separate_objects:
+        toolchain.copy_files(o, BUILD_TOOLCHAIN)