cmListFileLexer: Modify flex output to avoid Borland warning

Remove the "yyscanner = NULL" assignment from the end of the
yylex_destroy function because Borland warns that the value is never
used.
cmListFileCache: Use empty loop body instead of ;

This fixes the compiler warning

 Source/cmListFileCache.cxx:252: warning: suggest a space before ';' or
 explicit braces around empty body in 'while' statement
Merge topic 'cmake-syntax' into next

620bd42 cmListFileCache: Use empty loop body instead of ;
39a8cbe cmListFileLexer: Modify flex output to avoid Borland warning