GlueGen: NativeLibrary Fix, JNILibLoaderBase Enhancement

- NativeLibrary Fix
  - enumerateLibraryPaths(..):
     - Properly iterate through all prefix _and_ suffix.
     - Make public for JNILibLoaderBase.loadLibraryInternal(..)

  - isValidNativeLibraryName(..):
     - Stop iterating through prefix, if previously found
       but suffix doesn't match.

- JNILibLoaderBase.loadLibraryInternal(..) Enhancement
  - Mark customLibLoader FIXME: remove (we will get rid of jnlp.launcher.class)

  - If System.load(TempJarCache) and System.loadLibrary(plainLibName) fails,
    use NativeLibrary.enumerateLibraryPaths() w/ System.load(..) as last resort.

Tested on Linux x86_64 Java6 and OSX Java7 manually, no regressions expected.