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

src/osg/FragmentProgram.cpp

@@ -150,7 +150,7 @@ void FragmentProgram::apply(State& state) const
                                      _fragmentProgram.length(), _fragmentProgram.c_str());
 
         // Check for errors
-        GLint errorposition;
+        GLint errorposition = 0;
         glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorposition);
         if (errorposition != -1)
         {

src/osg/GLExtensions.cpp

@@ -129,7 +129,7 @@ bool osg::isGLExtensionOrVersionSupported(unsigned int contextID, const char *ex
                     #  ifndef GL_NUM_EXTENSIONS
                     #    define GL_NUM_EXTENSIONS 0x821D
                     #  endif
-                    GLint numExt;
+                    GLint numExt = 0;
                     glGetIntegerv( GL_NUM_EXTENSIONS, &numExt );
                     int idx;
                     for( idx=0; idx<numExt; idx++ )

src/osg/Shader.cpp

@@ -503,7 +503,7 @@ void Shader::PerContextShader::compileShader(osg::State& state)
 #if defined(OSG_GLES2_AVAILABLE)
     if (_shader->getShaderBinary())
     {
-        GLint numFormats;
+        GLint numFormats = 0;
         glGetIntegerv(GL_NUM_SHADER_BINARY_FORMATS, &numFormats);
 
         if (numFormats>0)

src/osg/State.cpp

@@ -899,7 +899,7 @@ void State::initializeExtensionProcs()
                                  osg::isGLExtensionSupported(_contextID,"GL_EXT_multitexture") ||
                                  OSG_GLES1_FEATURES)
     {
-        GLint maxTextureUnits;
+        GLint maxTextureUnits = 0;
         glGetIntegerv(GL_MAX_TEXTURE_UNITS,&maxTextureUnits);
         _glMaxTextureUnits = maxTextureUnits;
         _glMaxTextureCoords = maxTextureUnits;

src/osg/Texture.cpp

@@ -2258,6 +2258,7 @@ Texture::Extensions::Extensions(unsigned int contextID)
         OSG_INFO<<"Disabling _isNonPowerOfTwoTextureMipMappedSupported for GeForce FX hardware."<<std::endl;
     }
 
+    _maxTextureSize=0;
     glGetIntegerv(GL_MAX_TEXTURE_SIZE,&_maxTextureSize);
 
     char *ptr;
@@ -2274,6 +2275,7 @@ Texture::Extensions::Extensions(unsigned int contextID)
 
     if( _isMultiTexturingSupported )
     {
+       _numTextureUnits = 0;
        #if defined(OSG_GLES2_AVAILABLE) || defined(OSG_GL3_AVAILABLE)
            glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS,&_numTextureUnits);
        #else

src/osg/Texture2DArray.cpp

@@ -711,7 +711,9 @@ void Texture2DArray::Extensions::setupGLExtensions(unsigned int contextID)
     _isTexture3DSupported = OSG_GL3_FEATURES || isGLExtensionSupported(contextID,"GL_EXT_texture3D");
     _isTexture2DArraySupported = OSG_GL3_FEATURES || isGLExtensionSupported(contextID,"GL_EXT_texture_array");
 
+    _max2DSize = 0;
     glGetIntegerv(GL_MAX_TEXTURE_SIZE, &_max2DSize);
+    _maxLayerCount = 0;
     glGetIntegerv(GL_MAX_ARRAY_TEXTURE_LAYERS_EXT, &_maxLayerCount);
 
     setGLExtensionFuncPtr(_glTexImage3D, "glTexImage3D","glTexImage3DEXT");

src/osg/Texture3D.cpp

@@ -606,6 +606,7 @@ void Texture3D::Extensions::setupGLExtensions(unsigned int contextID)
     if (_isTexture3DFast) _isTexture3DSupported = true;
     else _isTexture3DSupported = strncmp((const char*)glGetString(GL_VERSION),"1.2",3)>=0;
     
+    _maxTexture3DSize = 0;
     glGetIntegerv(GL_MAX_3D_TEXTURE_SIZE, &_maxTexture3DSize);
 
     setGLExtensionFuncPtr(glTexImage3D,"glTexImage3D","glTexImage3DEXT");

src/osg/VertexProgram.cpp

@@ -150,7 +150,7 @@ void VertexProgram::apply(State& state) const
                                      _vertexProgram.length(), _vertexProgram.c_str());
 
         // Check for errors
-        GLint errorposition;
+        GLint errorposition = 0;
         glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorposition);
         if (errorposition != -1)
         {