make ./configure --help have all the options

Summary: This has always bugged me.

Now we have (with columns):

    usage: ./configure -Dvariable=argument ...\n
    Variables:
      -DCMAKE_BUILD_TYPE=Debug|Release|RelWithDebInfo|MinSizeRel    Sets build type                                                Default   Release
      -DALWAYS_ASSERT=ON|OFF                                        Enabled asserts in a release build                             Default   OFF
      -DDEBUG_APC_LEAK=ON|OFF                                       Allow easier debugging of apc leaks                            Default   OFF
      -DDEBUG_MEMORY_LEAK=ON|OFF                                    Allow easier debugging of memory leaks                         Default   OFF
      -DDISABLE_HARDWARE_COUNTERS=ON|OFF                            Disable hardware counters (for XenU systems)                   Default   OFF
      -DENABLE_COTIRE=ON|OFF                                        Speed up the build by precompiling headers                     Default   OFF
      -DENABLE_FULL_SETLINE=ON|OFF                                  Enable full setline function for debugger and code-coverage    Default   OFF
      -DENABLE_TRACE=ON|OFF                                         Enable tracing in release build                                Default   OFF
      -DENABLE_ZEND_COMPAT=ON|OFF                                   Enable Zend source compatibility                               Default   ON
      -DEXECUTION_PROFILER=ON|OFF                                   Enable the execution profiler                                  Default   OFF
      -DHOTPROFILER=ON|OFF                                          Enable support for the hot-profiler                            Default   OFF
      -DPACKED_TV=ON|OFF                                            Enable packed tv (typed value) compilation                     Default   OFF
      -DUSE_GOOGLE_CPU_PROFILER=ON|OFF                              Use Google cpu profiler                                        Default   OFF
      -DUSE_GOOGLE_HEAP_PROFILER=ON|OFF                             Use Google heap profiler                                       Default   OFF
      -DUSE_JEMALLOC=ON|OFF                                         Use jemalloc                                                   Default   ON
      -DUSE_TCMALLOC=ON|OFF                                         Use tcmalloc (if jemalloc is not used)                         Default   ON

and without columns

    usage: ./configure -Dvariable=argument ...\n
    Variables:
      -DCMAKE_BUILD_TYPE=Debug|Release|RelWithDebInfo|MinSizeRel : Sets build type : Default: Release
      -DALWAYS_ASSERT=ON|OFF : Enabled asserts in a release build : Default: OFF
      -DDEBUG_APC_LEAK=ON|OFF : Allow easier debugging of apc leaks : Default: OFF
      -DDEBUG_MEMORY_LEAK=ON|OFF : Allow easier debugging of memory leaks : Default: OFF
      -DDISABLE_HARDWARE_COUNTERS=ON|OFF : Disable hardware counters (for XenU systems) : Default: OFF
      -DENABLE_COTIRE=ON|OFF : Speed up the build by precompiling headers : Default: OFF
      -DENABLE_FULL_SETLINE=ON|OFF : Enable full setline function for debugger and code-coverage : Default: OFF
      -DENABLE_TRACE=ON|OFF : Enable tracing in release build : Default: OFF
      -DENABLE_ZEND_COMPAT=ON|OFF : Enable Zend source compatibility : Default: ON
      -DEXECUTION_PROFILER=ON|OFF : Enable the execution profiler : Default: OFF
      -DHOTPROFILER=ON|OFF : Enable support for the hot-profiler : Default: OFF
      -DPACKED_TV=ON|OFF : Enable packed tv (typed value) compilation : Default: OFF
      -DUSE_GOOGLE_CPU_PROFILER=ON|OFF : Use Google cpu profiler : Default: OFF
      -DUSE_GOOGLE_HEAP_PROFILER=ON|OFF : Use Google heap profiler : Default: OFF
      -DUSE_JEMALLOC=ON|OFF : Use jemalloc : Default: ON
      -DUSE_TCMALLOC=ON|OFF : Use tcmalloc (if jemalloc is not used) : Default: ON

Reviewed By: @JoelMarcey

Differential Revision: D1376802
match php5's memcache getoption

Summary: In

https://github.com/php-memcached-dev/php-memcached/blame/94f64446e782b0175e54b520b22b2fcc74988280/php_memcached.c#L2359

they check the result status is not `nullptr`. And on our version of the memcache library we werne't passing test/slow/ext_memcached/construct_persistent.php because we were returning `NULL` instead of `""`.

Reviewed By: @JoelMarcey

Differential Revision: D1376697
re-import curl tests

Summary: and lock in D1328961's changing of the tests. This should fix some travis tests.

Reviewed By: joelm, bertrand

Differential Revision: D1376639