Specify log level for CMake messages (less stderr)

Specify log level for CMake messages (less stderr)

Summary:
Specify message levels in CMake. Prefer STATUS (stdout).

As the default message mode (i.e. level) is NOTICE in CMake, more then necessary messages get printed to stderr. Some tools,  noticably ccmake treat this as an error and require additional confirmation and re-running CMake's configuration step.

This commit specifies a mode (either STATUS or WARNING or FATAL_ERROR)  instead of the default.

* I used `csearch -f 'llvm-project/.+(CMakeLists\.txt|cmake)' -l 'message\("'` to find all locations.
* Reviewers were chosen by the most common authors of specific files. If there are more suitable reviewers for these CMake changes, please let me know.

Patch by: Christoph Siedentop

Reviewers: zturner, beanz, xiaobai, kbobyrev, lebedev.ri, sgraenitz

Reviewed By: sgraenitz

Subscribers: mgorny, lebedev.ri, #sanitizers, lldb-commits, llvm-commits

Tags: #sanitizers, #lldb, #llvm

Differential Revision: https://reviews.llvm.org/D63370

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363821 91177308-0d34-0410-b5e6-96231b3b80d8