util: move compilere to a class

We do this to allow us to use descriptors for other related methods.

For now, util.compilere does the same thing. Upcoming patches will remove it.

mercurial/util.py

@@ -716,7 +716,8 try:
 except ImportError:
     _re2 = False
 
-def compilere(pat, flags=0):
+class _re(object):
+    def compile(self, pat, flags=0):
     '''Compile a regular expression, using re2 if possible
 
     For best performance, use only re2-compatible regexp features. The
@@ -740,6 +741,9 def compilere(pat, flags=0):
             pass
     return remod.compile(pat, flags)
 
+re = _re()
+compilere = re.compile
+
 _fspathcache = {}
 def fspath(name, root):
     '''Get name in the case stored in the filesystem