Remove ' characters from comments in cat2html.l

It turns out that Flex 2.6.4 trips over these, even when they are in comments.

ManOpen/cat2html.tproj/cat2html.l

@@ -116,7 +116,7 @@
 
     static void emitBackspacedLetters(char *charblock, yy_size_t lengthLeft, int doBold)
     {
-        /* If there's a trailing backspace, then both letters are deleted, so print nothing */
+        /* If there is a trailing backspace, then both letters are deleted, so print nothing */
         if (lengthLeft >= 4 && charblock[3] == '\010')
             return;
 
@@ -273,7 +273,7 @@ SGRSTART     \x1B\[
     /*
      *    nroff bullets
      */
-o\010"+"               emitRaw("·");   // "•" doesn't work
+o\010"+"               emitRaw("·");   // "•" does not work
 "+"\010o               emitRaw("·");
 o\010o\010"+"\010"+"   emitRaw("·");
 "+"\010"+\010"o\010o   emitRaw("·");
@@ -352,7 +352,7 @@ int main(int argc, char *argv[])
 
     yy_flex_debug = 0;
 
-    /* Keep the same args as cat2rtf, even though -s doesn't really make much difference */
+    /* Keep the same args as cat2rtf, even though -s does not really make much difference */
     while ((c = getopt(argc, argv, "dgGiISs:lH")) != EOF)
     {
         switch( c ) {