treewide: pkgs.pkgconfig -> pkgs.pkg-config, move pkgconfig to alias.nix

continuation of #109595

pkgconfig was aliased in 2018, however, it remained in
all-packages.nix due to its wide usage. This cleans
up the remaining references to pkgs.pkgsconfig and
moves the entry to aliases.nix.

python3Packages.pkgconfig remained unchanged because
it's the canonical name of the upstream package
on pypi.

pkgs/os-specific/linux/kernel/perf.nix

@@ -1,5 +1,5 @@
 { lib, stdenv, kernel, elfutils, python2, python3, perl, newt, slang, asciidoc, xmlto, makeWrapper
-, docbook_xsl, docbook_xml_dtd_45, libxslt, flex, bison, pkgconfig, libunwind, binutils
+, docbook_xsl, docbook_xml_dtd_45, libxslt, flex, bison, pkg-config, libunwind, binutils
 , libiberty, audit, libbfd, libopcodes, openssl, systemtap, numactl
 , zlib, withGtk ? false, gtk2 ? null
 }:
@@ -36,7 +36,7 @@ stdenv.mkDerivation {
   # perf refers both to newt and slang
   nativeBuildInputs = [
     asciidoc xmlto docbook_xsl docbook_xml_dtd_45 libxslt
-    flex bison libiberty audit makeWrapper pkgconfig python3
+    flex bison libiberty audit makeWrapper pkg-config python3
   ];
   buildInputs = [
     elfutils newt slang libunwind libbfd zlib openssl systemtap.stapBuild numactl