Remove gcc tools from script.

Replace all references to gcc tools with llvm tools. This change still
uses c++filt until llvm-cxxfilt is put in the prebuilts.

Test: Ran a backtrace through this script and the old script and verified
Test: no major differences.
Test: Ran unittests for symbol.py and stack_core.py.
Change-Id: Ic31c1a0707dae11c5037f9637943cd7932badf46

scripts/stack_core.py

@@ -263,7 +263,7 @@ class TraceConverter:
     else:
       apk_full_path = os.path.join(out_dir, apk)
     if not os.path.exists(apk_full_path):
-      print "Cannot find apk " + apk;
+      print "Cannot find apk " + apk
       return None, None
 
     cmd = subprocess.Popen(["zipinfo", "-v", apk_full_path], stdout=subprocess.PIPE)