Check if the environment variable TERM is defined before using it.

This fixes: <rdar://problem/6164279> scan-build gives error when invoked without TERM variable


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@56110 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed