Re-implement intel-mkl-tool

[termoshtt]

intel_mkl_tool::Entry is rewritten into intel_mkl_tool::Library.

Changes

• Seek given directory recursively.
• Do not use pkg-config crate. Manually call pkg-config --variable=prefix mkl-*-*-*, and seek libraries there.
• Do not seek all libraries. Seek only mkl.h, libmkl_core.{a,so}, and libiomp5.{a,so}
• Remove intel-mkl-tool CLI

[termoshtt]

cargo metadata of pkg-config crate looks wrong for mkl-static-*-* cases rust-lang/pkg-config-rs#135

I switch to use pkg-config only find library, generate cargo metadata manually, i.e. reverts #65