Add support for dev-libs/gmp (GNU MP library)

Packages describing “gmp” as local USE flag

Package“gmp” Flag Description
app-editors/emacsUse the GNU multiple precision arithmetic library (dev-libs/gmp) instead of the bundled mini-gmp subset
dev-haskell/bitvecLink against the GMP library for the ultimate performance of `zipBits`, `invertBits` and `countBits`. Users are strongly encouraged to enable this flag whenever possible.
dev-lang/ghcUse dev-libs/gmp for integer operations (works faster, but an external depend).

All packages providing a “gmp” USE flag (20)