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/FindPython.py

@@ -0,0 +1,50 @@
+import os
+import platform
+
+def FindPython():
+    all_abi_flags = ['m', 'mu', '']
+
+    python = "/usr"
+    abi_flags = "m"  # Most common for linux distros
+    version = "3.4"
+
+    _arch = platform.uname()[4] + "-linux-gnu"
+
+    # Determine ABI flags used on this system
+    include = os.path.join(python, "include")
+    for cur_flags in all_abi_flags:
+        inc = os.path.join(include, "python" + version + cur_flags, "Python.h")
+        if os.path.exists(inc):
+            abi_flags = cur_flags
+            break
+
+    # Find config.h. In some distros, such as ubuntu 12.10 they are not in standard include dir.
+    incconf = os.path.join(include, _arch, "python" + version + cur_flags)
+    if not os.path.exists(os.path.join(incconf, "pyconfig.h")):
+        incconf = ''
+
+    # Determine whether python is in /usr/lib or /usr/lib64
+    lib32 = os.path.join(python, "lib", "python" + version, "sysconfig.py")
+    lib64 = os.path.join(python, "lib64", "python" + version, "sysconfig.py")
+    if os.path.exists(lib32):
+        libpath = "${BF_PYTHON}/lib"
+    elif os.path.exists(lib64):
+        libpath = "${BF_PYTHON}/lib64"
+    else:
+        # roll back to default value
+        libpath = "${BF_PYTHON}/lib"
+
+    libpath_arch = libpath
+    _libpath_arch = os.path.join(python, "lib", _arch)  # No lib64 stuff with recent deb-like distro afaik...
+    _libs = ["libpython" + version + abi_flags + ext for ext in (".so", ".a")]
+    for l in _libs:
+        if not os.path.exists(os.path.join(libpath, l)) and os.path.exists(os.path.join(_libpath_arch, l)):
+            libpath_arch = os.path.join(libpath, _arch)
+            break
+
+    return {"PYTHON": python,
+            "VERSION": version,
+            "LIBPATH": libpath,
+            "LIBPATH_ARCH": libpath_arch,
+            "ABI_FLAGS": abi_flags,
+            "CONFIG": incconf}