Problem: CMakelist missing support for Windows Precompiled headers

Solution: Add precompiled flags to CMakeList.txt for faster compiles
+ bonus - removed compilation warning on Windows by adding
	 add_definitions (-D_WINSOCK_DEPRECATED_NO_WARNINGS)

CMakeLists.txt

@@ -382,6 +382,7 @@ if (WIN32)
     #   Socket limit is 16K (can be raised arbitrarily)
     add_definitions (-DFD_SETSIZE=16384)
     add_definitions (-D_CRT_SECURE_NO_WARNINGS)
+    add_definitions (-D_WINSOCK_DEPRECATED_NO_WARNINGS)
 endif ()
 
 if (MSVC)
@@ -622,6 +623,26 @@ if (ZMQ_BUILD_FRAMEWORK)
     COMMENT "Perf tools")
 endif ()
 
+if (MSVC)
+    # default for all sources is to use precompiled headers
+    foreach(source ${sources})
+        set_source_files_properties(${source}
+            PROPERTIES
+            COMPILE_FLAGS "/Yuprecompiled.hpp"
+            )
+    endforeach()
+    # create precompiled header
+    set_source_files_properties(${CMAKE_CURRENT_SOURCE_DIR}/src/precompiled.cpp
+        PROPERTIES
+        COMPILE_FLAGS "/Ycprecompiled.hpp"
+        )
+    # C and C++ can not use the same precompiled header
+    set_source_files_properties(${CMAKE_CURRENT_SOURCE_DIR}/src/tweetnacl.c
+        PROPERTIES
+        COMPILE_FLAGS "/Y-"
+        )
+endif ()
+
 
 #-----------------------------------------------------------------------------
 # output

tests/CMakeLists.txt

@@ -112,6 +112,7 @@ endif()
 # add location of platform.hpp for Windows builds
 if(WIN32)
     add_definitions(-DZMQ_CUSTOM_PLATFORM_HPP)
+    add_definitions(-D_WINSOCK_DEPRECATED_NO_WARNINGS)
     include_directories(../builds/msvc)
     link_libraries(Ws2_32.lib)
 endif()