* Don't override the CC and C++ environment variables
Fixes an issue where some makefiles override the user's CC and C++
environment variables.
* Restore test makefiles
* Test to change from CC = cc to CC = gcc for only needed files.
* Restore the whitespaces to their original state before the update in order to show the necessary file changes for the PR.
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Co-authored-by: Nino Tarantino <antonio.tarantino@nasa.gov>
