'pkg upgrade' on freebsd 11 broke 'X'

[Erdos New]

i did 'pkg-static upgrade' 'pkg upgrade' in order to install a new package on my freebsd 11/thinkpad t60 system. after the system reboot, 'X' failed to start.

output of Xorg.0.log file:
[   166.055] (II) RADEON(0): Acceleration enabled
[   166.055] (==) RADEON(0): DPMS enabled
[   166.055] (==) RADEON(0): Silken mouse enabled
[   166.055] (II) RADEON(0): Set up textured video
[   166.055] (II) RADEON(0): [XvMC] Associated with Radeon Textured Video.
[   166.055] (II) RADEON(0): [XvMC] Extension initialized.
[   166.055] (II) RADEON(0): RandR 1.2 enabled, ignore the following RandR disabled message.
[   166.056] (--) RandR disabled
[   166.206] (EE)
[   166.207] (EE) Backtrace:
[   166.209] (EE) 0: /usr/local/bin/X (OsInit+0x38a) [0x5abfba]
[   166.210] (EE) 1: /lib/libthr.so.3 (_pthread_sigmask+0x50d) [0x802daebbd]
[   166.212] (EE) 2: /lib/libthr.so.3 (_pthread_getspecific+0xe9f) [0x802daeacf]
[   166.214] (EE) 3: ? (?+0xe9f) [0x7ffffffffea2]
[   166.216] (EE) 4: /usr/local/llvm39/lib/libLLVM-3.9.so (_ZN4llvm13StringMapImpl15LookupBucketForENS_9StringRefE+0xc9) [0x808ec0319]
[   166.218] (EE) 5: /usr/local/llvm39/lib/libLLVM-3.9.so (LLVMParseCommandLineOptions+0x7cf) [0x808e8497f]
[   166.221] (EE) 6: /usr/local/llvm39/lib/libLLVM-3.9.so (LLVMParseCommandLineOptions+0x92c) [0x808e84c1c]
[   166.223] (EE) 7: /usr/local/llvm39/lib/libLLVM-3.9.so (_ZN4llvm2cl6Option11addArgumentEv+0x7c) [0x808e78dec]
[   166.226] (EE) 8: /usr/local/llvm35/lib/libLLVM-3.5.so (_ZN4llvm32createPPCTargetTransformInfoPassEPKNS_16PPCTargetMachineE+0xb92) [0x80da64752]
[   166.228] (EE) 9: /usr/local/llvm35/lib/libLLVM-3.5.so (LLVMInitializeARMTargetInfo+0x112) [0x80da6a094]
[   166.230] (EE) 10: /usr/local/llvm35/lib/libLLVM-3.5.so (_init+0xe) [0x80cbe25e4]
[   166.232] (EE) 11: ? (_rtld_is_dlopened+0x1532) [0x80081a3e2]
[   166.234] (EE) 12: ? (dlopen+0x191) [0x800816311]
[   166.235] (EE) 13: /usr/local/lib/xorg/modules/extensions/libglx.so (_init+0x1c544) [0x8046464e4]
[   166.237] (EE) 14: /usr/local/lib/xorg/modules/extensions/libglx.so (GlxSetVisualConfigs+0x66cd) [0x804636f3d]
[   166.239] (EE) 15: /usr/local/lib/xorg/modules/extensions/libglx.so (_init+0x1b056) [0x804643a16]
[   166.241] (EE) 16: /usr/local/bin/X (InitExtensions+0x61) [0x4ab921]
[   166.242] (EE) 17: /usr/local/bin/X (remove_fs_handlers+0x3a2) [0x43b4a2]
[   166.244] (EE) 18: /usr/local/bin/X (_start+0x17f) [0x42506f]
[   166.246] (EE) 19: ? (?+0x17f) [0x80083157f]
[   166.246] (EE)
[   166.246] (EE) Segmentation fault at address 0x0
[   166.246] (EE)
Fatal server error:
[   166.246] (EE) Caught signal 11 (Segmentation fault). Server aborting
[   166.246] (EE)
[   166.246] (EE)
Please consult the The X.Org Foundation support
         at http://wiki.x.org
 for help.
[   166.246] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[   166.246] (EE)
[   166.249] (EE) Server terminated with error (1). Closing log file.


any idea how to fix 'X'?