Added more tested platforms to README.

Author: ecorm

README.md

@@ -64,6 +64,8 @@ Tested Platforms
 This library has been tested with:
 
 - GCC 4.8.2, x86_64-linux-gnu, on Linux Mint 17 (based on Ubuntu 14.04)
+- GCC 4.9.2 on Debian 8.0 "jessie"
+- Xcode 6.3.1 (Clang 602.0.49) on OS X 10.10.3
 
 Usage Examples (using coroutines)
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