Hide some more LLVM-internal command line args.
Add fixes for Win64
Merge pull request #655 from klickverbot/hide-llvm-args

Hide some more LLVM-internal command line args.
Remove -noruntime as adverticed
Add -L=-lcurl to std.net.curl unit test.

There is no pragma to pull in this library. Therefore specify the lib on the command line.
Also remove emptymain.d as we now have the -main switch.
Fold in dmd-testsuite merge conflict fix.
Remove unused 'seenTemplateInstances' mechanism.
Use --gc-sections on Linux.

This was painful.
Disable a few more noisy warnings on recent GCC versions.
Merge pull request #654 from klickverbot/gc-sections

Use --gc-sections on Linux.
Merge pull request #657 from klickverbot/gcc-warnings

Disable a few more noisy warnings on recent GCC versions.
Hide '-disable-debug-info-verifier'.
Internalize everything but _Dmain when emitting a -singleobj executable.
This is just a first draft; there are certainly cases
where this still breaks (e.g. naked inline asm).

The general direction looks promising, though: Building a
fully optimized Phobos "Hello World" is noticably faster
with the internalizing enabled (0.7s vs 1s) on my machine.