eglib: Fix hardcoded library dependencies for Haiku

eglib: Fix hardcoded library dependencies for Haiku

  Math is beautiful
  A universal language
  Libraries differ
                    -- Andreas F.

Haiku neither has libm nor libdl. On Mac OS X, libm.dylib is just a symlink
to libSystem.dylib.

Introduce autoconf checks for these libraries.

	* configure.ac: Add checks for libm and libdl.
	* {src,test}/Makefile.am: Remove hardcoded library dependencies.
	Fixes compilation on Haiku.

v1 -> v2:
* Add checks for libm and libdl.

This commit is licensed under the MIT X11 license;
the Haiku poem is licensed under the CC Attribution 3.0 license.

svn path=/trunk/mono/; revision=155195