configure: Explicitly spell out first require_pkg_config() parameter

This is less confusing than encountering "" in the argument list.

configure

@@ -1139,7 +1139,6 @@ require_pkg_config(){
     shift
     pkg_version="$1"
     pkg="${1%% *}"
-    test "$name" = "" && name=$pkg
     check_pkg_config "$@" || die "ERROR: $pkg_version not found"
     add_cflags    $(get_safe "${pkg}_cflags")
     add_extralibs $(get_safe "${pkg}_extralibs")
@@ -4521,7 +4520,7 @@ case "$custom_allocator" in
         require libjemalloc jemalloc/jemalloc.h malloc -ljemalloc
     ;;
     tcmalloc)
-        require_pkg_config "" libtcmalloc gperftools/tcmalloc.h tc_malloc
+        require_pkg_config libtcmalloc libtcmalloc gperftools/tcmalloc.h tc_malloc
         malloc_prefix=tc_
     ;;
 esac
@@ -4657,8 +4656,8 @@ enabled avisynth          && require_header avisynth/avisynth_c.h
 enabled avxsynth          && require avxsynth "avxsynth/avxsynth_c.h dlfcn.h" dlopen -ldl
 enabled cuda              && require cuda cuda.h cuInit -lcuda
 enabled frei0r            && require_header frei0r.h
-enabled gnutls            && require_pkg_config "" gnutls gnutls/gnutls.h gnutls_global_init
-enabled libbs2b           && require_pkg_config "" libbs2b bs2b.h bs2b_open
+enabled gnutls            && require_pkg_config gnutls gnutls gnutls/gnutls.h gnutls_global_init
+enabled libbs2b           && require_pkg_config libbs2b libbs2b bs2b.h bs2b_open
 enabled libdc1394         && require_pkg_config libdc1394 libdc1394-2 dc1394/dc1394.h dc1394_new
 enabled libdcadec         && require libdcadec libdcadec/dca_context.h dcadec_context_create -ldcadec
 enabled libfaac           && require libfaac "stdint.h faac.h" faacEncGetVersion -lfaac
@@ -4668,10 +4667,10 @@ enabled libfreetype       && require_pkg_config libfreetype freetype2 "ft2build.
 enabled libgsm            && { for gsm_hdr in "gsm.h" "gsm/gsm.h"; do
                                    check_lib libgsm "${gsm_hdr}" gsm_create -lgsm && break;
                                done || die "ERROR: libgsm not found"; }
-enabled libhdcd           && require_pkg_config "" libhdcd "hdcd/hdcd_simple.h" hdcd_new
+enabled libhdcd           && require_pkg_config libhdcd libhdcd "hdcd/hdcd_simple.h" hdcd_new
 enabled libilbc           && require libilbc ilbc.h WebRtcIlbcfix_InitDecode -lilbc
 enabled libkvazaar        && require_pkg_config libkvazaar "kvazaar >= 0.8.1" kvazaar.h kvz_api_get
-enabled libmfx            && require_pkg_config "" libmfx "mfx/mfxvideo.h" MFXInit
+enabled libmfx            && require_pkg_config libmfx libmfx "mfx/mfxvideo.h" MFXInit
 enabled libmp3lame        && require "libmp3lame >= 3.98.3" lame/lame.h lame_set_VBR_quality -lmp3lame
 enabled libnpp            && require libnpp npp.h nppGetLibVersion -lnppi -lnppc
 enabled libopencore_amrnb && require libopencore_amrnb opencore-amrnb/interf_dec.h Decoder_Interface_init -lopencore-amrnb
@@ -4682,7 +4681,7 @@ enabled libopenjpeg       && { check_lib libopenjpeg openjpeg.h opj_version -lop
                                require_pkg_config libopenjpeg libopenjpeg1 openjpeg.h opj_version -DOPJ_STATIC; }
 enabled libopus           && require_pkg_config libopus opus opus_multistream.h opus_multistream_decoder_create
 enabled libpulse          && require_pkg_config libpulse libpulse-simple pulse/simple.h pa_simple_new
-enabled librtmp           && require_pkg_config "" librtmp librtmp/rtmp.h RTMP_Socket
+enabled librtmp           && require_pkg_config librtmp librtmp librtmp/rtmp.h RTMP_Socket
 enabled libschroedinger   && require_pkg_config libschroedinger schroedinger-1.0 schroedinger/schro.h schro_init
 enabled libsnappy         && require libsnappy snappy-c.h snappy_compress -lsnappy
 enabled libspeex          && require_pkg_config libspeex speex speex/speex.h speex_decoder_init -lspeex
@@ -4713,7 +4712,7 @@ enabled libvpx            && require_pkg_config libvpx "vpx >= 1.3.0" vpx/vpx_co
     fi
 }
 enabled libwavpack        && require libwavpack wavpack/wavpack.h WavpackOpenFileOutput  -lwavpack
-enabled libwebp           && require_pkg_config "" libwebp webp/encode.h WebPGetEncoderVersion
+enabled libwebp           && require_pkg_config libwebp libwebp webp/encode.h WebPGetEncoderVersion
 enabled libx264           && require_pkg_config libx264 x264 "stdint.h x264.h" x264_encoder_encode &&
                              require_cpp_condition x264.h "X264_BUILD >= 118" &&
                              { check_cpp_condition x264.h "X264_MPEG2" &&