Utilities/Sphinx: Avoid using deprecated sphinx APIs

Sphinx has deprecated `sphinx.util.pycompat.htmlescape` and
`sphinx.builders.qthelp.QtHelpBuilder`.  We only import these as part of
a monkey-patch to work around a bug in versions of sphinx before 1.7.2,
so make that code path conditional.  The imports are not deprecated on
the versions where we need them.

Utilities/Sphinx/cmake.py

@@ -57,25 +57,6 @@ CMakeLexer.tokens["root"] = [
   #  (r'[^<>\])\}\|$"# \t\n]+', Name.Exception),            # fallback, for debugging only
 ]
 
-# Monkey patch for sphinx generating invalid content for qcollectiongenerator
-# https://bitbucket.org/birkenfeld/sphinx/issue/1435/qthelp-builder-should-htmlescape-keywords
-from sphinx.util.pycompat import htmlescape
-from sphinx.builders.qthelp import QtHelpBuilder
-old_build_keywords = QtHelpBuilder.build_keywords
-def new_build_keywords(self, title, refs, subitems):
-  old_items = old_build_keywords(self, title, refs, subitems)
-  new_items = []
-  for item in old_items:
-    before, rest = item.split("ref=\"", 1)
-    ref, after = rest.split("\"")
-    if ("<" in ref and ">" in ref):
-      new_items.append(before + "ref=\"" + htmlescape(ref) + "\"" + after)
-    else:
-      new_items.append(item)
-  return new_items
-QtHelpBuilder.build_keywords = new_build_keywords
-
-
 from docutils.parsers.rst import Directive, directives
 from docutils.transforms import Transform
 try:
@@ -93,13 +74,36 @@ from sphinx.util.nodes import make_refnode
 from sphinx import addnodes
 
 sphinx_before_1_4 = False
+sphinx_before_1_7_2 = False
 try:
     from sphinx import version_info
     if version_info < (1, 4):
         sphinx_before_1_4 = True
+    if version_info < (1, 7, 2):
+        sphinx_before_1_7_2 = True
 except ImportError:
     # The `sphinx.version_info` tuple was added in Sphinx v1.2:
     sphinx_before_1_4 = True
+    sphinx_before_1_7_2 = True
+
+if sphinx_before_1_7_2:
+  # Monkey patch for sphinx generating invalid content for qcollectiongenerator
+  # https://github.com/sphinx-doc/sphinx/issues/1435
+  from sphinx.util.pycompat import htmlescape
+  from sphinx.builders.qthelp import QtHelpBuilder
+  old_build_keywords = QtHelpBuilder.build_keywords
+  def new_build_keywords(self, title, refs, subitems):
+    old_items = old_build_keywords(self, title, refs, subitems)
+    new_items = []
+    for item in old_items:
+      before, rest = item.split("ref=\"", 1)
+      ref, after = rest.split("\"")
+      if ("<" in ref and ">" in ref):
+        new_items.append(before + "ref=\"" + htmlescape(ref) + "\"" + after)
+      else:
+        new_items.append(item)
+    return new_items
+  QtHelpBuilder.build_keywords = new_build_keywords
 
 class CMakeModule(Directive):
     required_arguments = 1