CMake: Add libm to list of system libs printed by llvm-config.

This is required by the interpreter library, and also matches the autoconf
behavior.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221147 91177308-0d34-0410-b5e6-96231b3b80d8
Test commit.

Fixes two typos.

Change-Id: I129f647de8933e1d8f0dc9941bcb91602edce7e2

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221148 91177308-0d34-0410-b5e6-96231b3b80d8