Add a parameter to the FIND_STD_PROGRAM macro that allows an alternate name

Add a parameter to the FIND_STD_PROGRAM macro that allows an alternate name
for the command line options. This helps with situations where the executable
name sought is too generic and a more meaningful name needs to be used for
the command line options. It also helps satisfy picky project leaders.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22461 91177308-0d34-0410-b5e6-96231b3b80d8