Implement equality and hash for compiled patterns

Author: msimacek

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_re.txt

@@ -59,6 +59,8 @@
 *graalpython.lib-python.3.test.test_re.ReTests.test_not_literal
 *graalpython.lib-python.3.test.test_re.ReTests.test_nothing_to_repeat
 *graalpython.lib-python.3.test.test_re.ReTests.test_other_escapes
+*graalpython.lib-python.3.test.test_re.ReTests.test_pattern_compare
+*graalpython.lib-python.3.test.test_re.ReTests.test_pattern_compare_bytes
 *graalpython.lib-python.3.test.test_re.ReTests.test_pickling
 *graalpython.lib-python.3.test.test_re.ReTests.test_qualified_re_split
 *graalpython.lib-python.3.test.test_re.ReTests.test_qualified_re_sub

graalpython/lib-graalpython/_sre.py

@@ -306,6 +306,16 @@ def __repr__(self):
             sflags = "|".join(flag_items)
         return "re.compile(%r%s%s)" % (self.pattern, sep, sflags)
 
+    def __eq__(self, other):
+        if self is other:
+            return True
+        if type(other) != SRE_Pattern:
+            return NotImplemented
+        return self.pattern == other.pattern and self.flags == other.flags
+
+    def __hash__(self):
+        return hash(self.pattern) * 31 ^ hash(self.flags)
+
     def _search(self, pattern, string, pos, endpos, sticky=False):
         pattern = self.__tregex_compile(pattern, self.flags_str + ("y" if sticky else ""))
         input_str = string