configure: fix pkg-config check for libtls

This was not accounted for during merge and is required due to
the refactor in commit 93ccba96df.

Signed-off-by: sfan5 <sfan5@live.de>
Signed-off-by: James Almer <jamrial@gmail.com>

configure

@@ -5894,7 +5894,7 @@ enabled libssh            && require_pkg_config libssh libssh libssh/sftp.h sftp
 enabled libspeex          && require_pkg_config libspeex speex speex/speex.h speex_decoder_init
 enabled libtesseract      && require_pkg_config libtesseract tesseract tesseract/capi.h TessBaseAPICreate
 enabled libtheora         && require libtheora theora/theoraenc.h th_info_init -ltheoraenc -ltheoradec -logg
-enabled libtls            && { use_pkg_config libtls libtls tls.h tls_configure ||
+enabled libtls            && { check_pkg_config libtls libtls tls.h tls_configure ||
                                require libtls tls.h tls_configure -ltls; }
 enabled libtwolame        && require libtwolame twolame.h twolame_init -ltwolame &&
                              { check_lib libtwolame twolame.h twolame_encode_buffer_float32_interleaved -ltwolame ||