srand() & simple rand() supporing seed
use js variable for rand_seed
Revert "use js variable for rand_seed"

This reverts commit 3e31f83ac762e34b266b7888aec161bb2b843dd1.
fix rand_r; add rand_r in test_rand
Merge branch 'rand' of github.com:coolwanglu/emscripten into incoming
misc cleanups
use all 32 bits in rand_r
use Math.imul in rand_r
asmify rand_r
asmify rand