lang/ghc: add NO_CCACHE=yes
This fixes the following build error with ccache (probably caused
by CCACHE_DIR not propagated through the build properly):
[1 of 1] Compiling Main ( Setup.hs, Setup.o ) ccache: error: Failed to create directory /nonexistent/.ccache/6/3: Permission denied `clang' failed in phase `Assembler'. (Exit code: 1)
Approved by: portmgr blanket