cast_test, cast_test_static fail, Apple linker bug on *-darwin10

[fangism]

On i686-apple-darwin10, there's a nasty linker bug that causes catastrophic failure in nearly all tests. The simplest place to test for this is in the src/ directory. A simple 'make check' there should pass easily on ALL platforms. If 'cast_test' fails, then you know you've triggered this linker bug.

Workaround: LDFLAGS=-Wl,-no_compact_linkedit

For 64b, x64_64-darwin10, you need, in addition, to set the environment variable during configure AND make: export MACOSX_DEPLOYMENT_TARGET=10.4 to avoid an undefined reference link error to dyld_stub_binding_helper.