Move test.c to a better place

[ViralBShah]

It is really odd to have a test.c file in JULIAHOME. It would be nice to have a better location for it in the source tree, and also a self-descriptive name.

[JeffBezanson]

Is it used anywhere? Looked to me like it was committed by mistake.

[staticfloat]

Agreed, although it might be useful to have some small C tests on hand. For instance, I have more than once, asked people to compile something like openblas_test.c to help narrow down the PCRE build problems. Would something like that go in contrib if it were to eventually be included?

[ViralBShah]

Contrib is the right place if needed.

[vtjnash]

This looks like my file. I didn't mean to commit it, especially since it was to test clang, not Julia.