fix makefile
fix: keep g++ attributes to g++ only

prevent wannabe compilers from parsing GNUC-only code
(clang++ apparently defines __GNUC__)
fix clang warning
Fix of wrong stats of pistol's ammo on HUD, when player holds nade and akimbo disappears.
To test the bug: take akimbo, take grenade, press "g"  and wait for akimbo disappearing.
Then stats on HUD shows, that player has pistol with 0 ammo, instead of full magazine.
Merge remote-tracking branch 'assaultcube/master' into wiosna