x64FPURoundMode: use fesetround() instead of asm
x64FPURoundMode: always set x87 precision

Set the x87 precision, even on x64. Since we are using x87 instructions
in the JIT now, we can't guarantee that x87 precision will never
influence Dolphin on x64.
Merge pull request #329 from Tilka/rounding

Small FPU settings changes
Travis CI test.
Adds a StdBasicString.h header to Common

Android has broken C99 support in it's NDK. This hasn't been too much of an issue since most uses of the disabled features have been in the WX GUI.
This has become a bit more of an issue since we can't use std::to_string in common code due to it being disabled in basic_string.h due to the
_GLIBCXX_USE_C99 define not being set.

This StdBasicString header adds the disabled code block back in with the few functions removed that we can't use without C99.
Once/If the Android NDK fully supports C99, this header can be removed.
This PR is required for PR #331 as it is trying to use to_string in Source/Core/VideoBackends/OGL/FramebufferManager.cpp