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/development/libraries/kerberos/heimdal.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchFromGitHub, autoreconfHook, pkgconfig, python2, perl, yacc, flex
+{ stdenv, fetchFromGitHub, autoreconfHook, pkg-config, python2, perl, yacc, flex
 , texinfo, perlPackages
 , openldap, libcap_ng, sqlite, openssl, db, libedit, pam
 , CoreFoundation, Security, SystemConfiguration
@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
 
   patches = [ ./heimdal-make-missing-headers.patch ];
 
-  nativeBuildInputs = [ autoreconfHook pkgconfig python2 perl yacc flex texinfo ]
+  nativeBuildInputs = [ autoreconfHook pkg-config python2 perl yacc flex texinfo ]
     ++ (with perlPackages; [ JSON ]);
   buildInputs = optionals (stdenv.isLinux) [ libcap_ng ]
     ++ [ db sqlite openssl libedit openldap pam]

pkgs/development/libraries/kerberos/krb5.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, pkgconfig, perl, yacc, bootstrap_cmds
+{ stdenv, fetchurl, pkg-config, perl, yacc, bootstrap_cmds
 , openssl, openldap, libedit, keyutils
 
 # Extra Arguments
@@ -49,7 +49,7 @@ stdenv.mkDerivation rec {
          "ac_cv_printf_positional=yes"
        ];
 
-  nativeBuildInputs = [ pkgconfig perl ]
+  nativeBuildInputs = [ pkg-config perl ]
     ++ optional (!libOnly) yacc
     # Provides the mig command used by the build scripts
     ++ optional stdenv.isDarwin bootstrap_cmds;