Remove all ARCH references.

Replaced with ARCH_IS_32BIT since that's the only thing truly
necessary to work.

This also makes the register regex much more lenient, but it appears
to be strict enough that it doesn't seem to capture arbitrary lines
when run through logcat.

Removed the StripPC function and verified that an arm crash that
ends in 1 still works.

Removed the architecture.py script, it is old and I don't see anyone
using it.

Modify the reading of the lines to ignore any errors in the input.

Test: All unit tests pass.
Test: Symbolized arm and arm64 tombstones
Test: Symbolized x86 and x86_64 tombstones
Test: Ran through a logcat and verified it caught the bug but
Test: didn't print any extra information.
Change-Id: I6a65ecaad68da1d56864db32ff434512e4df0d89

scripts/stack

@@ -44,7 +44,10 @@ def main():
 
   args = parser.parse_args()
   if args.arch:
-    symbol.ARCH = args.arch
+    if args.arch == "arm" or args.arch == "x86":
+      symbol.ARCH_IS_32BIT = True
+    else:
+      symbol.ARCH_IS_32BIT = False
   if args.symbols_dir:
     symbol.SYMBOLS_DIR = args.symbols_dir
   if args.symbols_zip:
@@ -56,10 +59,11 @@ def main():
   symbol.VERBOSE = args.verbose
   if args.file == '-':
     print("Reading native crash info from stdin")
+    sys.stdin.reconfigure(errors='ignore')
     f = sys.stdin
   else:
     print("Searching for native crashes in %s" % args.file)
-    f = open(args.file, "r")
+    f = open(args.file, "r", errors='ignore')
 
   lines = f.readlines()
   f.close()