TCLTK_INTERNAL= is interpreted as unset in makefile

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@32241 15284696-431f-4ddb-bdfa-cd5b030d7da7

macosx/ReadMe.rtf

@@ -369,11 +369,11 @@ By default, the application is built expecting a local copy of Tcl/Tk inside the
 \i This is currently hardwired to Tcl/Tk 8.4.
 \i0 \
 \
-If you want to try building GRASS using Tcl/Tk Aqua (not recommended), set TCLTK_INTERNAL to nothing before compiling:\
+If you want to try building GRASS using Tcl/Tk Aqua (not recommended), set TCLTK_INTERNAL to a space before compiling:\
 \
 \pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\ql\qnatural\pardirnatural
 
-\f1\fs20 \cf0 export TCLTK_INTERNAL=\
+\f1\fs20 \cf0 export TCLTK_INTERNAL=" "\
 \pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\ql\qnatural\pardirnatural
 
 \f0\fs24 \cf0 \