Add Conan Building For Development (#432)

external/snappy/patches/1.1.9-0004-rtti-by-default.patch

@@ -0,0 +1,20 @@
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -53,8 +53,6 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+   add_definitions(-D_HAS_EXCEPTIONS=0)
+ 
+   # Disable RTTI.
+-  string(REGEX REPLACE "/GR" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /GR-")
+ else(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+   # Use -Wall for clang and gcc.
+   if(NOT CMAKE_CXX_FLAGS MATCHES "-Wall")
+@@ -78,8 +76,6 @@ endif()
+   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions")
+ 
+   # Disable RTTI.
+-  string(REGEX REPLACE "-frtti" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-rtti")
+ endif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+ 
+ # BUILD_SHARED_LIBS is a standard CMake variable, but we declare it here to make