Correct preprocessor docs

Blatently incorrect information removed.

Author: wsfulton

Doc/Manual/Preprocessor.html

@@ -162,9 +162,7 @@ <H2><a name="Preprocessor_condition_compilation">10.3 Conditional Compilation</a
 <p>
 Interface files can look at these symbols as necessary to change the
 way in which an interface is generated or to mix SWIG directives with
-C code. These symbols are also defined within the C code generated by
-SWIG (except for the symbol `<tt>SWIG</tt>' which is only defined
-within the SWIG compiler).
+C code.
 </p>
 
 <H2><a name="Preprocessor_nn5">10.4 Macro Expansion</a></H2>