Minor bugfixes to BLAS compatibility layer.

Details:
- Changed bla_amax.c so that i?amax() routines now correctly return 0
  if ( n < 1 || incx <= 0 ).
- Changed bla_rotg.c and bla_rotmg.c to use bli_fabs() macro instead of
  f2c's abs() macro for float and double cases.
- Thanks to Murtaza Ali for suggesting the two fixes above.
- Updated label of fnormv to normfv in testsuite/input.operations.