Fix libvogltrace64 crashing bash

- Could repro via this command:

LD_PRELOAD=$(readlink -f libvogltrace64.so) bash -i -c "if true; then
echo blah; fi"

- Problem was our global constructors allocating memory before our
memory system initialized.
- Signal handlers getting called and constructors getting called
again.
- Assert code allocing memory (which is bad when memory code is
asserting).

Killed most of the static constructors. Since we are a library
being loaded into other applications, we should not use them.

http://llvm.org/docs/CodingStandards.html#do-not-use-static-constructors

- Enable global-constructors warning by default with Clang.
- Add Wno-global-constructors to vogleditor makefile.
- g_gl_enums -> get_gl_enums()
- g_get_desc -> get_gl_get_desc()
- g_vogl_internal_texture_formats -> get_vogl_internal_texture_formats()
- g_internal_format_hash_map -> get_internal_format_hash_map
- g_dynamic_module_cache
- Move g_well_known_string_hashes to local function.
- g_vogl_capture_path, g_vogl_capture_basename -> get_vogl_intercept_data()
- g_vogl_trace_mutex -> get_vogl_trace_mutex()
- g_vogl_trace_writer -> get_vogl_trace_writer()
- g_context_manager -> get_context_manager

- COMPILER_GCC -> COMPILER_GCCLIKE for JPGD_NORETURN

- Switch g_vogl_has_been_initialized to bool (doesn't need
to be atomic w/ pthread_once).
- Add create_if_not_set param to vogl_context
get_current().

There are still several global ctor warnings that I
need to go through and fix.