Fix mutual recursion inside other parentheses stack overflow bug.

ChangeLog

@@ -37,6 +37,10 @@ interacting badly with the code for computing the amount of space needed to
 compile the pattern, leading to a buffer overflow. This bug was discovered by
 the LLVM fuzzer.
 
+10. A pattern such as /((?2)+)((?1))/ which has mutual recursion nested inside
+other kinds of group caused stack overflow at compile time. This bug was
+discovered by the LLVM fuzzer.
+
 
 Version 10.10 06-March-2015
 ---------------------------

src/pcre2_compile.c

@@ -1331,8 +1331,8 @@ for (code = first_significant_code(code + PRIV(OP_lengths)[*code], TRUE);
       empty_branch = FALSE;
       do
         {
-        if (!empty_branch && could_be_empty_branch(code, endcode, utf, cb, NULL))
+        if (!empty_branch && could_be_empty_branch(code, endcode, utf, cb, 
-          empty_branch = TRUE;
+          recurses)) empty_branch = TRUE;
         code += GET(code, 1);
         }
       while (*code == OP_ALT);

testdata/testinput2

@@ -4236,4 +4236,9 @@ a random value. /Ix
     ** Failers 
     aaa 
 
+# JIT gives a different error message for the infinite recursion
+
+"(*NO_JIT)((?2)+)((?1)){"
+    abcd{
+
 # End of testinput2 

testdata/testoutput2

@@ -14198,4 +14198,10 @@ No match
     aaa 
 No match
 
+# JIT gives a different error message for the infinite recursion
+
+"(*NO_JIT)((?2)+)((?1)){"
+    abcd{
+Failed: error -52: nested recursion at the same subject position
+
 # End of testinput2