android: fix some compiler warnings

(cherry picked from commit 7f415ce5879ad607b33e644e4b9e34ededfa51b2)

src/render/opengles2/SDL_shaders_gles2.h

@@ -63,7 +63,7 @@ typedef enum
 
 const Uint8 *GLES2_GetShader(GLES2_ShaderType type);
 const Uint8 *GLES2_GetShaderInclude(GLES2_ShaderIncludeType type);
-GLES2_ShaderIncludeType GLES2_GetTexCoordPrecisionEnumFromHint();
+GLES2_ShaderIncludeType GLES2_GetTexCoordPrecisionEnumFromHint(void);
 
 #endif /* SDL_VIDEO_RENDER_OGL_ES2 */