Build libgcrypt and libgpg-error with Xcode 5.

- Update libgcrypt to version 1.5.3.
- Change SDKVERSION to 7.0.
- Fix build-libcrypt.sh and build-libgpg-error.sh to make it compile with Xcode 5 installed.
No longer depend on /usr/bin/llvm-cpp-4.2.

Use cpp included in Xcode 5 package instead of /usr/bin/llvm-cpp-4.2.
Improve build-libgcrypt.sh script.
Update libgpg-error to version 1.12.
Merge pull request #6 from michaelwermeester/master

Build libgcrypt and libgpg-error with Xcode 5.
Fixes #5