Update liboauth from 0.8.9 to 0.9.4.

Changes since previous version:

version 0.9.4
  - fixed possible memory corrution in oauth_curl_get
  thanks to Bruce Rosen for reporting this issue

version 0.9.3
- yet more build-system fixes:
  - allow to override HASH_LIBS and CURL_LIBS using envoronment variables
  - include them in .pc and tests/Makefile.am

version 0.9.2
- fixed typo in build-system (LDFLAGS, -Wl,--as-needed detection)

version 0.9.1
- fixed typo in API:
  oauth_time_indepenent_equals[_n] is now deprecated in favor of
oauth_time_independent_equals[_n]
- added check for 'Wl,--as-needed' linker flag.

version 0.9.0
- fixed typo in pkg-config file.

With thanks to Brad Harder for the nudge.

(agc)