Fix issue #7, add #pragma once to generated header

VkCppGenerator.cpp

@@ -1867,6 +1867,8 @@ int main( int argc, char **argv )
   std::ofstream ofs( "vk_cpp.h" );
   ofs << licenseHeader << std::endl;
 
+  ofs << std::endl << "#pragma once" << std::endl;
+
   ofs << "#include <array>" << std::endl
       << "#include <cstdint>" << std::endl
       << "#include <cstring>" << std::endl

vulkan/vk_cpp.h

@@ -24,8 +24,11 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+
+#pragma once
 #include <array>
-#include <stdint.h>
+#include <cstdint>
+#include <cstring>
 #include <vulkan/vulkan.h>
 #ifdef VKCPP_ENHANCED_MODE
 # include <vector>