RFR (S): 8015266: fix some -Wsign-compare warnings in adlc

[Christian Thalinger]

http://javaweb.us.oracle.com/~cthaling/webrev/8015266/webrev/

8015266: fix some -Wsign-compare warnings in adlc
Reviewed-by:

Some warnings I've found while hacking on the build system.

src/share/vm/adlc/archDesc.cpp
src/share/vm/adlc/dict2.cpp
src/share/vm/adlc/formssel.cpp
src/share/vm/adlc/formssel.hpp
src/share/vm/adlc/output_c.cpp