Patch for Review: Compile each classfile individually unless --enable-libgcj-multifile

[Per Bothner]

>>It might make sense though to turn --enable-libgcj-multifile on whenever
>>--enable-intermodule is present (presumably, anyone building with
>>--enable-intermodule has plenty of memory).  That can be changed later.

I think the default should be whatever makes bootstrap builds
fastest on most machines, especially if it also produces
better code.  The speed of the compile-debug-edit cycle is not
as important, especially if there is an option to improve it.

My preference for the default:  Build largish groups of classes
(perhaps by package) at once, but probably not everything.
-- 
	--Per Bothner
per@bothner.com   http://per.bothner.com/