Fix ImageIO building on Linux

Author: q4a

README.md

@@ -18,12 +18,10 @@ Building: mkdir bin && cd bin && cmake ../src
 
 Current status (Linux):
 Build Failed:
-[ 70%] Building CXX object Externals/NVTT/src/nvimage/CMakeFiles/nvimage.dir/ImageIO.cpp.o
-In function ‘nv::FloatImage* nv::ImageIO::loadFloat(const char*)’:
-xray-16/src/Externals/NVTT/src/nvimage/ImageIO.cpp:138:10: error: cannot convert ‘bool’ to ‘nv::FloatImage*’ in return
-   return false;
-          ^~~~~
-
+[ 82%] Building CXX object xrCore/CMakeFiles/xrCore.dir/clsid.cpp.o
+xray-16/src/xrCore/_types.h:14:24: error: expected initializer before ?s64?
+ typedef signed __int64 s64;
+                        ^~~
 
 
 If you find a bug or have an enhancement request, file an [Issue](https://github.com/openxray/xray-16/issues).
@@ -34,5 +32,5 @@ Pull requests appreciated! However, the following things should be taken into co
 * Major changes should be discussed before implementation
 * Follow the [procedures](doc/procedure)
 
-Be advised that this project is not sanctioned by GSC Game World in any way – and they remain the copyright holders
+Be advised that this project is not sanctioned by GSC Game World in any way ? and they remain the copyright holders
 of all the original source code.

src/Externals/NVTT/src/nvimage/ImageIO.cpp

@@ -135,7 +135,7 @@ FloatImage * nv::ImageIO::loadFloat(const char * fileName)
 	StdInputStream stream(fileName);
 
 	if (stream.isError()) {
-		return false;
+		return NULL;
 	}
 
 	return loadFloat(fileName, stream);
@@ -233,7 +233,7 @@ Image * nv::ImageIO::loadTGA(Stream & s)
 		case TGA_TYPE_INDEXED:
 			if( tga.colormap_type!=1 || tga.colormap_size!=24 || tga.colormap_length>256 ) {
 				nvDebug( "*** ImageIO::loadTGA: Error, only 24bit paletted images are supported.\n" );
-				return false;
+				return NULL;
 			}
 			pal = true;
 			break;
@@ -254,7 +254,7 @@ Image * nv::ImageIO::loadTGA(Stream & s)
 
 		default:
 			nvDebug( "*** ImageIO::loadTGA: Error, unsupported image type.\n" );
-			return false;
+			return NULL;
 	}
 
 	const uint pixel_size = (tga.pixel_size/8);