Remove gflags dependency from Bazel build.

This was forgotten back in google#97.

Fix compilation error on Mac.

_exit is declared in unistd.h

Create 32bit and 64bit build configuration for Windows. (google#28)

Makefiles still compile for whatever architecture local C compiler
compiles for by default.

Merge pull request google#6 from robryk/static-linking

Fix static linking.

fix formatting in readme