warn on missing blacklist, better errmsg

[GoogleCodeExporter]

clang -mllvm -asan-blacklist=asan_blacklist.ignore
currently fails on a missing asan_blacklist.ignore file.

I improved the error message.

And I prefer a warning over the fatal exit as I have multiple blacklist 
files in relative paths, but only for certain subprojects.
Missing a blacklist file should just produce a warning IMHO.

patch attached.

Original issue reported on code.google.com by reini.urban on 30 Nov 2011 at 4:12

Attachments:

• blacklist-warn.patch

[GoogleCodeExporter]

More informative warning is ok, I'll commit it with some other changes. 
Warning instead of error is not ok, imho. 

Original comment by konstant...@gmail.com on 1 Dec 2011 at 6:08

• Changed state: Accepted

[GoogleCodeExporter]

Just landed the change (llvm r145611) that calls report_fatal_error when the 
blacklist is not found. 

Original comment by konstant...@gmail.com on 1 Dec 2011 at 6:59

• Changed state: Fixed