Add -no-opengles3 to configure to avoid QT_OPENGL_ES_3 define.

This can be helpful for packaging and when one wants to limit the
features to ES 2.0 to ensure the same code is used on both build
machine and deployment machine. It also prevents inclusion of
GLES3/gl3.h. Windows configure.exe doesn't do auto detection of
GLES3 so it does not get the additional option.

Change-Id: I8750b41635e41bd0ac41d9d59d93570f7d2196e6
Reviewed-by: Thiago Macieira <[email protected]>
Reviewed-by: Laszlo Agocs <[email protected]>

configure

@@ -643,6 +643,7 @@ CFG_XRANDR=runtime
 CFG_XRENDER=auto
 CFG_MITSHM=auto
 CFG_OPENGL=auto
+CFG_OPENGLES3=yes # still depends on CFG_OPENGL, so auto in practice
 CFG_OPENVG=auto
 CFG_OPENVG_LC_INCLUDES=no
 CFG_OPENVG_SHIVA=auto
@@ -1279,6 +1280,13 @@ while [ "$#" -gt 0 ]; do
             UNKNOWN_OPT=yes
         fi
         ;;
+    opengles3)
+        if [ "$VAL" = "no" ]; then
+            CFG_OPENGLES3="no"
+        else
+            UNKNOWN_OPT=yes
+        fi
+        ;;
     openvg)
         if [ "$VAL" = "auto" ] || [ "$VAL" = "yes" ] || [ "$VAL" = "no" ]; then
             CFG_OPENVG="$VAL"
@@ -5333,7 +5341,7 @@ fi
 # compile-time differentiation and including the version specific (but backwards
 # compatible) ES headers (for example, GLES3/gl31.h). Other than that, there is
 # no difference in the configuration, even the library is the same.
-if [ "$CFG_OPENGL" = "es2" ]; then
+if [ "$CFG_OPENGL" = "es2" ] && [ "$CFG_OPENGLES3" = "yes" ]; then
     if compileTestWithPkgConfig glesv2 unix/opengles3 "OpenGL ES 3.0" ""; then
         # Add a define for ES3, in addition to ES and ES2.
         QCONFIG_FLAGS="$QCONFIG_FLAGS QT_OPENGL_ES_3"