Added a tool to more accurately count the lines of code. The previous

Added a tool to more accurately count the lines of code. The previous
utility, getsrcs.sh suffered from two problems: (1) it generated command
lines too long for some platforms and (2) it searched the projects diretory
which now contains the llvm-test module (in nightly tester) but we don't
want to include the test code in our LOC calculation. This script should
be maintained as LLVM adds new top level directories that contain source
code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16199 91177308-0d34-0410-b5e6-96231b3b80d8