From David Fries, "Fix remote X11 crash querying GL_NUM_EXTENSIONS

In osg::isGLExtensionOrVersionSupported in src/osg/GLExtensions.cpp when
using indirect X11 rendering,
glGetIntegerv( GL_NUM_EXTENSIONS, &numExt );
is leaving numExt uninitilized causing the following glGetStringi to
return NULL when the extension number isn't present.  Passing NULL to
std::string() then crashes.  This is with the following nVidia driver.
OpenGL version string: 3.3.0 NVIDIA 256.35

I went ahead and initialized some of the other variables before
glGetInitegerv in other files as well.  I don't know for sure
which ones can fail, so I don't know which are strictly required.
"

examples/osgautocapture/osgautocapture.cpp

@@ -99,7 +99,7 @@ public:
 #if defined(OSG_GLES1_AVAILABLE) || defined(OSG_GLES2_AVAILABLE)
                  if (pixelFormat == GL_RGB)
                  {
-                    GLint value;
+                    GLint value = 0;
                     #ifndef GL_IMPLEMENTATION_COLOR_READ_FORMAT
                         #define GL_IMPLEMENTATION_COLOR_READ_FORMAT 0x8B9B
                     #endif