[PATCH] fix gamma symbol for static linking and new targets

[Joseph Myers]

On Mon, 2 Oct 2017, Szabolcs Nagy wrote:

> it seems drem and pow10 symbols are also affected.

pow10 is deliberately obsoleted and should not be present for new ports or 
static linking and should be a compat symbol for existing ports.

We might reasonably consider doing the same for drem (it's an __USE_MISC 
symbol, not from any supported standard, and an exact alias of remainder).

-- 
Joseph S. Myers
joseph@codesourcery.com