Define _HAS_EXCEPTIONS=0 to avoid MSVC C4530 warning.

Avoid "warning C4530: C++ exception handler used, but unwind semantics
are not enabled. Specify /EHsc" when compiling MSVC's <xlocale> by
disabling the exception code in MSVC's STL using _HAS_EXCEPTIONS=0.

Change-Id: I75aeb445d58cc9fb44467a6044386ae6b519cca8
Reviewed-on: https://boringssl-review.googlesource.com/3111
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6d2c39f..643f351 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,6 +9,7 @@
 	# Disable warnings for implicit integer narrowing.
 	set(CMAKE_C_FLAGS "/wd4267")
 	set(CMAKE_CXX_FLAGS "/wd4267")
+	add_definitions(-D_HAS_EXCEPTIONS=0)
 endif()
 
 if((CMAKE_COMPILER_IS_GNUCXX AND CMAKE_C_COMPILER_VERSION VERSION_GREATER "4.5.99") OR