Fix pattern overrun in utf extended mode for a # comment that hit the end.

ChangeLog

@@ -117,6 +117,10 @@ when the POSIX API was in use.
 compiled. A non-installed  binary to run the test function locally, called
 pcre2fuzzcheck is also compiled.
 
+18. In UTF-8 or UTF-16 modes with PCRE2_EXTENDED (/x) set and a non-zero-
+terminated pattern, if a # comment ran on to the end of the pattern, one or 
+more code units past the end were being read.
+
 
 Version 10.22 29-July-2016
 --------------------------

src/pcre2_compile.c

@@ -2326,7 +2326,7 @@ while (ptr < ptrend)
           }
         ptr++;
 #ifdef SUPPORT_UNICODE
-        if (utf) FORWARDCHAR(ptr);
+        if (utf) FORWARDCHARTEST(ptr, ptrend);
 #endif
         }
       continue;  /* Next character in pattern */

testdata/testinput5

@@ -1731,6 +1731,8 @@
 
 /'(*UTF)'/hex 
 
+/'#('/hex,extended,utf
+
 /a(?<=A\XB)/utf
 
 /ab(?<=A\RB)/utf

testdata/testoutput5

@@ -4167,6 +4167,8 @@ No match
 
 /'(*UTF)'/hex 
 
+/'#('/hex,extended,utf
+
 /a(?<=A\XB)/utf
 Failed: error 125 at offset 1: lookbehind assertion is not fixed length