qjackctl: fix build errors

qmake-qt5 cannot be found by the configure script. This is fixed adding
the prefix of the Qt5 installation as a configure option.
Building with LLVM/Clang raises an error related to a variable sized
array. This is fixed by patching a source file to use a dynamically
allocated array instead.

Fix missing link time dependency for qjackctl

This error was detected by running brew audit --strict --online
qjackctl which showed following error:

     * Formulae are required to declare all linked dependencies.
         Please add all linked dependencies to the formula with:
               depends_on "portaudio" => :linked

Fixes #3278.
Closes #3281.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Formula/qjackctl.rb

@@ -14,6 +14,14 @@ class Qjackctl < Formula
   depends_on "autoconf" => :build
   depends_on "qt5"
   depends_on "jack"
+  depends_on "portaudio" => :linked
+
+  # Fixes varaible length array error with LLVM/Clang
+  # Reported upstream: https://github.com/rncbc/qjackctl/issues/17
+  patch do
+    url "https://github.com/rncbc/qjackctl/commit/e92de08f7fd7c62ff1fb4f0330583f321a2a9aae.patch"
+    sha256 "cbb7cc72e0086b8e6df24c8c3a462dc0e9297f095573adb7a3cf98502a1902d4"
+  end
 
   def install
     system "./autogen.sh"
@@ -21,7 +29,8 @@ class Qjackctl < Formula
                           "--enable-qt5",
                           "--disable-dbus",
                           "--disable-xunique",
-                          "--prefix=#{prefix}"
+                          "--prefix=#{prefix}",
+                          "--with-qt5=#{Formula["qt5"].opt_prefix}"
 
     system "make", "install"
     prefix.install bin/"qjackctl.app"