Update Ceres to latest upstream version

Brings new bounds limiting and also prepares build system
for the changes in the upstream.

Namely shared_ptr header and namespace is now being detected
by a build system rather than by hacks in the code.

This commit includes some changes to auto-detection flags
in SCons, presumably adding more consistency there. This
is main changes which are suppoed to be reviewed here.

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D581

build_files/scons/Modules/FindUnorderedMap.py

@@ -0,0 +1,38 @@
+def FindUnorderedMap(conf):
+    """
+    Detect unordered_map availability
+    """
+
+    namespace = None
+    header = None
+
+    if conf.CheckCXXHeader("unordered_map"):
+        # Even so we've found unordered_map header file it doesn't
+        # mean unordered_map and unordered_set will be declared in
+        # std namespace.
+        #
+        # Namely, MSVC 2008 have unordered_map header which declares
+        # unordered_map class in std::tr1 namespace. In order to support
+        # this, we do extra check to see which exactly namespace is
+        # to be used.
+
+        if conf.CheckType('std::unordered_map<int, int>', language = 'CXX', includes="#include <unordered_map>"):
+            print("-- Found unordered_map/set in std namespace.")
+            namespace = 'std'
+            header = 'unordered_map'
+        elif conf.CheckType('std::tr1::unordered_map<int, int>', language = 'CXX', includes="#include <unordered_map>"):
+            print("-- Found unordered_map/set in std::tr1 namespace.")
+            namespace = 'std::tr1'
+            header = 'unordered_map'
+        else:
+            print("-- Found <unordered_map> but can not find neither std::unordered_map nor std::tr1::unordered_map.")
+    elif conf.CheckCXXHeader("tr1/unordered_map"):
+        print("-- Found unordered_map/set in std::tr1 namespace.")
+        namespace = 'std::tr1'
+        header = 'tr1/unordered_map'
+    else:
+        print("-- Unable to find <unordered_map> or <tr1/unordered_map>. ")
+
+    conf.env['WITH_UNORDERED_MAP_SUPPORT'] = namespace and header
+    conf.env['UNORDERED_MAP_NAMESPACE'] = namespace
+    conf.env['UNORDERED_MAP_HEADER'] = header