bug#49990: [PATCH] gnu: Fix classpath-bootstrap compilation

[muradm]

This patch fixes issue in the way that it:
a) calculates the result before call to 
(*env)->ReleaseStringUTFChars
b) attempt to trick gcc optimizations by complicating path

I suppose issue is with what (*env)->ReleaseStringUTFChars does 
and
how.

One should note that similar approach is not applicable to 
substitute
in package definition.

Why not just build ancient code with ancient gcc?