new test cc_cblas (closes #95)

[miroi]

• extended math_libs.cmake for C headers detection
• static_linking test included
• no int64 in the cc_cblas test
• both Linux and Windows (OpenBLAS)

[bast]

Sorry for being pedantic but the allocated arrays in the test are never freed. Every executable should exit with zero allocation at the end.

[miroi]

fixed

[bast]

Thanks!