Revert "Enable the new text layout engine by default"

This reverts commit d79f43d0.

Breaks MacOSX tinderbox, need to figure out why a totally unrelated test
is broken.

vcl/README.vars

@@ -6,7 +6,7 @@ SAL_USE_VCLPLUGIN - use a VCL plugin
 SAL_NO_NWF - disable native widgets
 SAL_FORCEDPI - force a specific DPI (gtk & gtk3 plugins only)
 SAL_FORCE_HC - force high-contrast mode
-SAL_NO_COMMON_LAYOUT - disable CommonSalLayout layout engine for text layout
+SAL_USE_COMMON_LAYOUT - use CommonSalLayout layout engine for text layout
 
 VCL_DOUBLEBUFFERING_AVOID_PAINT - don't paint the buffer, useful to see where we do direct painting
 VCL_DOUBLEBUFFERING_FORCE_ENABLE - enable double buffered painting

vcl/source/gdi/sallayout.cxx

@@ -770,7 +770,7 @@ bool SalLayout::IsSpacingGlyph( sal_GlyphId nGlyph )
 
 bool SalLayout::UseCommonLayout()
 {
-    static bool bUse = getenv("SAL_NO_COMMON_LAYOUT") == nullptr;
+    static bool bUse = getenv("SAL_USE_COMMON_LAYOUT") != nullptr;
     return bUse;
 }