example3: replace old stb_image 1.18 with stb_image 2.30 and stb_image_write 1.16

Pulled from https://github.com/nothings/stb
Commit 013ac3beddff3dbffafd5177e7972067cd2b5083

Author: illwieckz

example3/CMakeLists.txt

@@ -6,7 +6,6 @@ include_directories(
 # Defines the source code for the library
 set(EXAMPLE3_SRCS
   ${CMAKE_CURRENT_SOURCE_DIR}/example3.cpp
-  ${CMAKE_CURRENT_SOURCE_DIR}/stb_image.h
 )
 
 add_executable(example3 ${EXAMPLE3_SRCS})

example3/example3.cpp

@@ -20,10 +20,16 @@
 #pragma warning(disable : 4100)  // unreferenced formal parameter
 #pragma warning(disable : 4127)  // conditional expression is constant
 #endif
+
+#define STB_IMAGE_IMPLEMENTATION
 #include "stb_image.h"
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
 
 using namespace crnlib;
 
+typedef unsigned int uint;
+
 const uint cDXTBlockSize = 4;
 
 static int print_usage() {