This checkin also breaks OS X framework builds.  For some reason, framework builds are compiled with the gcc -fno-common option.  The code in configure.ac to add that option dates back to the initial OS X framework support (c3c87ce4afdc from 2001).  It's not clear to me why we use that option just in the case of framework builds (I suspect it may no longer be necessary) but the fact is that we have been and currently still do.  And, in any case, the GCC description of -fno-common (https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html) suggests that there may be valid reasons to use it on some platforms or that other compilers might behave this way by default.  A simple way to produce the error on Linux is:

./configure OPT="-fno-common" && make

[...]
gcc -pthread   -o Programs/_freeze_importlib Programs/_freeze_importlib.o Modules/getbuildinfo.o Parser/acceler.o Parser/grammar1.o Parser/listnode.o Parser/node.o Parser/parser.o Parser/bitset.o Parser/metagrammar.o Parser/firstsets.o Parser/grammar.o Parser/pgen.o Parser/myreadline.o Parser/parsetok.o Parser/tokenizer.o Objects/abstract.o Objects/accu.o Objects/boolobject.o Objects/bytes_methods.o Objects/bytearrayobject.o Objects/bytesobject.o Objects/cellobject.o Objects/classobject.o Objects/codeobject.o Objects/complexobject.o Objects/descrobject.o Objects/enumobject.o Objects/exceptions.o Objects/genobject.o Objects/fileobject.o Objects/floatobject.o Objects/frameobject.o Objects/funcobject.o Objects/iterobject.o Objects/listobject.o Objects/longobject.o Objects/dictobject.o Objects/memoryobject.o Objects/methodobject.o Objects/moduleobject.o Objects/namespaceobject.o Objects/object.o Objects/obmalloc.o Objects/capsule.o Objects/rangeobject.o Objects/setobject.o Objects/sliceobject.o Objects/structseq.o Objects/tupleobject.o Objects/typeobject.o Objects/unicodeobject.o Objects/unicodectype.o Objects/weakrefobject.o Python/_warnings.o Python/Python-ast.o Python/asdl.o Python/ast.o Python/bltinmodule.o Python/ceval.o Python/compile.o Python/codecs.o Python/dynamic_annotations.o Python/errors.o Python/frozenmain.o Python/future.o Python/getargs.o Python/getcompiler.o Python/getcopyright.o Python/getplatform.o Python/getversion.o Python/graminit.o Python/import.o Python/importdl.o Python/marshal.o Python/modsupport.o Python/mystrtoul.o Python/mysnprintf.o Python/peephole.o Python/pyarena.o Python/pyctype.o Python/pyfpe.o Python/pyhash.o Python/pylifecycle.o Python/pymath.o Python/pystate.o Python/pythonrun.o Python/pytime.o Python/random.o Python/structmember.o Python/symtable.o Python/sysmodule.o Python/traceback.o Python/getopt.o Python/pystrcmp.o Python/pystrtod.o Python/pystrhex.o Python/dtoa.o Python/formatter_unicode.o Python/fileutils.o Python/dynload_shlib.o   Python/thread.o Modules/config.o Modules/getpath.o Modules/main.o Modules/gcmodule.o  Modules/_threadmodule.o  Modules/signalmodule.o  Modules/posixmodule.o  Modules/errnomodule.o  Modules/pwdmodule.o  Modules/_sre.o  Modules/_codecsmodule.o  Modules/_weakref.o  Modules/_functoolsmodule.o  Modules/_operator.o  Modules/_collectionsmodule.o  Modules/itertoolsmodule.o  Modules/atexitmodule.o  Modules/_stat.o  Modules/timemodule.o  Modules/_localemodule.o  Modules/_iomodule.o Modules/iobase.o Modules/fileio.o Modules/bytesio.o Modules/bufferedio.o Modules/textio.o Modules/stringio.o  Modules/zipimport.o  Modules/faulthandler.o  Modules/_tracemalloc.o Modules/hashtable.o  Modules/symtablemodule.o  Modules/xxsubtype.o -lpthread -ldl  -lutil   -lm
Python/pylifecycle.o:(.bss+0x20): multiple definition of `Py_FrozenFlag'
Programs/_freeze_importlib.o:(.data+0x0): first defined here
collect2: error: ld returned 1 exit status
Makefile:710: recipe for target 'Programs/_freeze_importlib' failed
make: *** [Programs/_freeze_importlib] Error 1

The OS X version of ld helpfully lists the modules:

duplicate symbol _Py_FrozenFlag in:
    Programs/_freeze_importlib.o
    Python/pylifecycle.o

I'm also not sure why the Py_FrozenFlag definition was added to _freeze_importlib.c in the first place.  Reverting it with the following patch seems to solve the problem in the few configurations I tried (OS X framework, OS X non-shared, Linux non-shared, Linux shared).

diff Programs/_freeze_importlib.c
--- a/Programs/_freeze_importlib.c      Tue May 05 12:04:35 2015 -0700
+++ b/Programs/_freeze_importlib.c      Tue May 05 17:10:39 2015 -0700
@@ -12,8 +12,6 @@
 #include <unistd.h>
 #endif

-int Py_FrozenFlag = 1;  /* Suppress errors from getpath.c */
-
 /* To avoid a circular dependency on frozen.o, we create our own structure
    of frozen modules instead, left deliberately blank so as to avoid
    unintentional import of a stale version of _frozen_importlib. */