Bug 387935, Always build JS as C++, r=benjamin

--HG--
rename : js/src/js.c => js/src/js.cpp
rename : js/src/jsapi.c => js/src/jsapi.cpp
rename : js/src/jsarena.c => js/src/jsarena.cpp
rename : js/src/jsarray.c => js/src/jsarray.cpp
rename : js/src/jsatom.c => js/src/jsatom.cpp
rename : js/src/jsbool.c => js/src/jsbool.cpp
rename : js/src/jscntxt.c => js/src/jscntxt.cpp
rename : js/src/jscpucfg.c => js/src/jscpucfg.cpp
rename : js/src/jsdate.c => js/src/jsdate.cpp
rename : js/src/jsdbgapi.c => js/src/jsdbgapi.cpp
rename : js/src/jsdhash.c => js/src/jsdhash.cpp
rename : js/src/jsdtoa.c => js/src/jsdtoa.cpp
rename : js/src/jsemit.c => js/src/jsemit.cpp
rename : js/src/jsexn.c => js/src/jsexn.cpp
rename : js/src/jsfile.c => js/src/jsfile.cpp
rename : js/src/jsfun.c => js/src/jsfun.cpp
rename : js/src/jsgc.c => js/src/jsgc.cpp
rename : js/src/jshash.c => js/src/jshash.cpp
rename : js/src/jsinterp.c => js/src/jsinterp.cpp
rename : js/src/jsiter.c => js/src/jsiter.cpp
rename : js/src/jskwgen.c => js/src/jskwgen.cpp
rename : js/src/jslock.c => js/src/jslock.cpp
rename : js/src/jslog2.c => js/src/jslog2.cpp
rename : js/src/jslong.c => js/src/jslong.cpp
rename : js/src/jsmath.c => js/src/jsmath.cpp
rename : js/src/jsnum.c => js/src/jsnum.cpp
rename : js/src/jsobj.c => js/src/jsobj.cpp
rename : js/src/jsopcode.c => js/src/jsopcode.cpp
rename : js/src/jsparse.c => js/src/jsparse.cpp
rename : js/src/jsprf.c => js/src/jsprf.cpp
rename : js/src/jsregexp.c => js/src/jsregexp.cpp
rename : js/src/jsscan.c => js/src/jsscan.cpp
rename : js/src/jsscope.c => js/src/jsscope.cpp
rename : js/src/jsscript.c => js/src/jsscript.cpp
rename : js/src/jsstr.c => js/src/jsstr.cpp
rename : js/src/jsutil.c => js/src/jsutil.cpp
rename : js/src/jsxdrapi.c => js/src/jsxdrapi.cpp
rename : js/src/jsxml.c => js/src/jsxml.cpp
rename : js/src/prmjtime.c => js/src/prmjtime.cpp