Set _PYSTON_API inside our build system instead of setting it when we detect a c++11 compiler

This allows c++11 extensions to use the C API

from_cpython/Include/pyport.h

@@ -16,13 +16,6 @@
 #define PYSTON_NOEXCEPT
 #endif
 
-// HACK: we should set this manually rather than cluing off of the C++ version
-#ifdef __cplusplus
-#if __cplusplus > 199711L
-#define _PYSTON_API
-#endif
-#endif
-
 #define Py_PROTO(x) x
 
 // Pyston change: these are just hard-coded for now:

src/CMakeLists.txt

 set(CMAKE_INCLUDE_CURRENT_DIR ON)
-set(CMAKE_CXX_FLAGS_DEBUG "-g -DBINARY_SUFFIX= -DBINARY_STRIPPED_SUFFIX=_stripped -DPy_BUILD_CORE")
-set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -fstrict-aliasing -enable-tbaa -DNVALGRIND -DBINARY_SUFFIX=_release -DBINARY_STRIPPED_SUFFIX= -DPy_BUILD_CORE")
+set(CMAKE_CXX_FLAGS_DEBUG "-g -DBINARY_SUFFIX= -DBINARY_STRIPPED_SUFFIX=_stripped -DPy_BUILD_CORE -D_PYSTON_API")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -fstrict-aliasing -enable-tbaa -DNVALGRIND -DBINARY_SUFFIX=_release -DBINARY_STRIPPED_SUFFIX= -DPy_BUILD_CORE -D_PYSTON_API")
 
 execute_process(COMMAND git rev-parse HEAD WORKING_DIRECTORY ${CMAKE_SOURCE_DIR} OUTPUT_VARIABLE GITREV OUTPUT_STRIP_TRAILING_WHITESPACE)
 set_source_files_properties(jit.cpp PROPERTIES COMPILE_DEFINITIONS "GITREV=${GITREV}")

test/unittests/CMakeLists.txt

-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-undef")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-undef -D_PYSTON_API")
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
 
 add_definitions(-DGTEST_HAS_RTTI=0 ${LLVM_DEFINITIONS})