RFR: 8013786: JDK-8013480 broke configure on solaris

[Tim Bell]

Erik:

> Unfortunately the change for bug JDK-8013480 broke the build on Solaris:
>
> Configure no longer looks for cc and CC instead of gcc and g++ on 
> solaris. This is caused by use of the macro AC_COMPILE_IFELSE in 
> platform.m4, before the compilers have been initialized. We have 
> implemented our platform dependent initialization of the compilers in 
> toolchain.m4, which is executed after platform.m4. The macro 
> AC_COMPILE_IFELSE runs AC_PROG_CC implicitly and sets CC to gcc, which 
> is the default. Once done, AC_PROG_CC cannot be run again and so we 
> get stuck with that value.
>
> This patch moves these checks to toolchain.m4, after the compilers 
> have been initialized. I'm currently running a jprt job verifying that 
> this indeed works on all platforms.
>
> http://cr.openjdk.java.net/~erikj/8013786/webrev.root.01

Looks good.  Thanks, Erik

Tim