Revert "Enable the new text layout engine by default"

This reverts commit d79f43d0bebbe7b1f8d68d50734737aea9fe839d.

Breaks MacOSX tinderbox, need to figure out why a totally unrelated test
is broken.
diff --git a/vcl/README.vars b/vcl/README.vars
index d50a03b..10e6356 100644
--- a/vcl/README.vars
+++ b/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
diff --git a/vcl/source/gdi/sallayout.cxx b/vcl/source/gdi/sallayout.cxx
index 2e09aaf..b865ff9 100644
--- a/vcl/source/gdi/sallayout.cxx
+++ b/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;
}