8153416: unexport javah from jdk.compiler module
Reviewed-by: mchung

8076543: Add @modules as needed to the langtools tests
Reviewed-by: jjg, shurailine

6990390: javah -help produces help screen with extraneous output
Reviewed-by: darcy

6893932: javah help screen lists -h and -? but does not accept them
Reviewed-by: darcy