Move gl_text's OpenGL header inclusion to the cpp file

Originally committed to SVN as r5906.

aegisub/src/gl_text.cpp

@@ -47,6 +47,12 @@
 #include "gl_text.h"
 #include "utils.h"
 
+#ifdef __APPLE__
+#include <OpenGL/gl.h>
+#else
+#include <GL/gl.h>
+#endif
+
 /// @class OpenGLTextGlyph
 /// @brief Struct storing the information needed to draw a glyph
 struct OpenGLTextGlyph {

aegisub/src/gl_text.h

@@ -43,12 +43,6 @@
 #include <wx/font.h>
 #endif
 
-#ifdef __APPLE__
-#include <OpenGL/gl.h>
-#else
-#include <GL/gl.h>
-#endif
-
 struct OpenGLTextGlyph;
 class OpenGLTextTexture;