Since bug 341901 landed we don't have *any* version info in the JS dll. This is bad, we should have the default Mozilla stuff, if nothing else.

This patch adjusts configure to set version vars from milestone.txt (same as all other sections of the codebase), sets the LIBRARY_NAME to contain major.minor version, installs headers into a version-specific subdir, adjusts js-config generation appropriately for all changes, and adds generation of a pkg-config .pc file (currently installed only on linux, but please add for all arches that are appropriate). This patch corresponds nicely with the symbol-versioning patch found in attachment 681995 [details] [diff] [review] Patch also addresses bug 481878

..forgot; patch also sets a variable NSPR_MINVER in configure, so that the configure checks for external NSPR will propagate through to the 'Requires:' section of the .pc file.

Comment on attachment 682018 [details] [diff] [review] Implement versioning ... reviewed on IRC with ted, this fix isn't appropriate to this particular bug. Dunno how to remove attachments, but i'll stop usurping the bug now and use bug 812265 instead This bug might be appropriate to depend on the solution here, though, given version info is made available within the js/src build system.