title: Package gtk4 was not found in the pkg-config search path
body: <p>I've installed MSYS2 on Windows 7 and I have successfully executed</p>
  <pre><code>pacman -S mingw-w64-x86_64-gtk3
  </code></pre>
  <p>(the above as per <strong>Step 2</strong> of <a href="https://www.gtk.org/docs/installations/windows/" rel="nofollow noreferrer">Setting up GTK for Windows</a>) and</p>
  <pre><code>pacman -S mingw-w64-x86_64-toolchain base-devel
  </code></pre>
  <p>but when I try to compile the <a href="https://www.gtk.org/docs/getting-started/hello-world/" rel="nofollow noreferrer">hello world</a> with</p>
  <pre><code>gcc -o hello-world-gtk hello-world-gtk.c `pkg-config --cflags --libs gtk4`
  </code></pre>
  <p>I get the following</p>
  <pre><code>Package gtk4 was not found in the pkg-config search path.
  Perhaps you should add the directory containing `gtk4.pc'
  to the PKG_CONFIG_PATH environment variable
  Package 'gtk4', required by 'virtual:world', not found
  bash: gcc: command not found
  </code></pre>
  <p>If I try from MinGW 64-bit shell the output is</p>
  <pre><code>MyHome@MyHome-PC MINGW64 ~
  $ gcc -o hello-world-gtk hello-world-gtk.c `pkg-config --cflags --libs gtk4`
  Package gtk4 was not found in the pkg-config search path.
  Perhaps you should add the directory containing `gtk4.pc'
  to the PKG_CONFIG_PATH environment variable
  Package 'gtk4', required by 'virtual:world', not found
  hello-world-gtk.c:1:10: fatal error: gtk/gtk.h: No such file or directory
      1 | #include &lt;gtk/gtk.h&gt;
        |          ^~~~~~~~~~~
  compilation terminated.
  </code></pre>
  <p>I've also checked that</p>
  <pre><code>$ echo $PKG_CONFIG_PATH
  /mingw64/lib/pkgconfig:/mingw64/share/pkgconfig
  </code></pre>