Move GetOptInc to the common namespace

Summary:
GetOptInc provides getopt(), getopt_long() and getopt_long_only().

Windows (for defined(_MSC_VER)) doesn't ship with all of the getopt(3) family members and needs all of them. NetBSD requires only getopt_long_only(3).

While there fix the code for clang diagnostics.

Author: Kamil Rytarowski

Reviewers: joerg

Subscribers: labath, zturner, lldb-commits

Differential Revision: http://reviews.llvm.org/D12582

llvm-svn: 246843