kill bitrig-gcc
make gfortran bootstrap with clang
oops, bump gfortran
Revert "kill bitrig-gcc"

This reverts commit 18b646193fd422d2ed5b7ada7bb1052a44e39f99.

Sorry that went in by accident!
make R compile on bitrig
Use arc4random() as the entropy source.
disable colours by default in clang

make '-fno-color-diagnostics' the default in clang. to enable colours,
use -fcolor-diagnostics.

ok natano@ patrick@ jcv@