configure.ac: Check for pkg-config, fix double BUILD_ALSA_SB_RC report.
configure.ac: Check for pkg-config, fix double BUILD_ALSA_SB_RC report.

Kudos: Age Boosma for testing.

stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc