math: Add support for auto static math tests

It basically copy the already in place rules for dynamic tests for
auto-generated math functions for all support types.  To avoid the
need to duplicate .inc files, a .SECONDEXPANSION rules is adeed for
the gen-libm-test.py generation.

New tests are added on the new rules 'libm-test-funcs-auto-static',
'libm-test-funcs-noauto-static', and 'libm-test-funcs-narrow-static';
similar to the non-static counterparts.

To avoid add extra build and disk requirement, the new math static
tests are only enable with a new define 'build-math-static-tests'.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>