When a build number is not specified, the JRE_RELEASE_VERSION define contains a date and timestamp. Thus ccache cannot cache the object files for longer than a minute since the define is passed to the compilation of all source files. This change passes JRE_RELEASE_VERSION only to vm_version.cpp and adds a function jre_release_version() to Abstract_VM_Version. This allows all other source files to be ccached.
Reviewed-by: ohair, rottenha
301215b860