slideshow: windows build fixes

Change-Id: I9032af7583f0cf97664d2f84d5aead0cb1547c1a
(cherry picked from commit 3b397f8a)

slideshow/source/engine/OGLTrans/generic/OGLTrans_TransitionImpl.cxx

@@ -1921,7 +1921,7 @@ void HoneycombTransition::displaySlides_( double nTime, sal_Int32 glLeavingSlide
 
     // The back (entering) slide needs to be drawn before the front (leaving) one in order for blending to work.
 
-    const float borderSize = 0.15;
+    const float borderSize = 0.15f;
 
     CHECK_GL_ERROR();
     glUniform1f(maSelectedTextureLocation, 0.0);
@@ -1956,7 +1956,7 @@ std::shared_ptr<OGLTransitionImpl> makeHoneycomb()
     const int NY = 21;
 
     TransitionSettings aSettings;
-    aSettings.mnRequiredGLVersion = 3.2;
+    aSettings.mnRequiredGLVersion = 3.2f;
 
     Primitives_t aSlide;
     Primitive aHexagon;

slideshow/source/engine/OGLTrans/generic/OGLTrans_TransitionImpl.hxx

@@ -228,18 +228,18 @@ private:
     GLint m_nNormalLocation = -1;
     GLint m_nTexCoordLocation = -1;
 
-    GLuint m_nVertexArrayObject = -1;
+    GLuint m_nVertexArrayObject = 0u;
 
     std::vector<int> m_nFirstIndices;
 
 protected:
     /** GLSL program object
      */
-    GLuint m_nProgramObject = 0;
+    GLuint m_nProgramObject = 0u;
 
     /** VBO in which to put primitive data
      */
-    GLuint m_nVertexBufferObject = -1;
+    GLuint m_nVertexBufferObject = 0u;
 };