Suggest using CMake rather than autotools.

The configure script 1) can't find newer versions of Qt, thanks to the
Qt developers not supplying any .pc files and 2) doesn't look for useful
frameworks, so it's not the best way to build Wireshark on macOS any
more.  Discuss CMake instead.

Change-Id: I28befffab010221e2e17e37f5beaf8b732974190
Reviewed-on: https://code.wireshark.org/review/23990
Reviewed-by: Guy Harris <guy@alum.mit.edu>

README.macos

@@ -22,16 +22,27 @@ Qt packages and source code from
 
 or use the tools/macos-setup.sh script described below.
 
+You should have CMake installed; you can download binary distributions
+for macOS from
+
+	https://cmake.org/download/
+
+The Wireshark source includes an autoconf configure script; however,
+that script cannot find recent versions of Qt for macOS, and will not
+try to find macOS frameworks that Wireshark can use to improve the user
+experience, so we don't recomment using the configure script.
+
 The tools/macos-setup.sh script can be used to download, patch as
 necessary, build as necessary, and install those libraries and the
-libraries on which they depend; it will, by default, also install other
+libraries on which they depend, along with tools such as CMake; it will,
-libraries that can be used by Wireshark and TShark.  The versions of
+by default, also install other libraries that can be used by Wireshark
-libraries to download are specified by variables set early in the
+and TShark.  The versions of libraries and tools to download are
-script; you can comment out the settings of optional libraries if you
+specified by variables set early in the script; you can comment out the
-don't want them downloaded and installed.  Before running the
+settings of optional libraries if you don't want them downloaded and
-tools/macos-setup.sh script, and before attempting to build Wireshark,
+installed.  Before running the tools/macos-setup.sh script, and before
-make sure your PKG_CONFIG_PATH environment variable's setting includes
+attempting to build Wireshark, make sure your PKG_CONFIG_PATH
-both /usr/X11/lib/pkgconfig and /usr/local/lib/pkgconfig.
+environment variable's setting includes both /usr/X11/lib/pkgconfig and
+/usr/local/lib/pkgconfig.
 
 The tools/macos-setup.sh script must be run from the top-level source
 directory.
@@ -48,25 +59,28 @@ elsewhere, such as
 
 After you have installed those libraries:
 
-If you are building from a Git tree, rather than from a source
+	make a directory in which Wireshark is to be built, separate
-distribution tarball, run the autogen.sh script.  This should not be
+	from the top-level source directory for Wireshark - it can be a
-necessary if you're building from a source distribution tarball, unless
+	subdirectory of that top-level source directory;
-you've added new source files to the Wireshark source.
 
-Then run the configure script, and run make to build Wireshark.
+	cd to that directory, and run CMake, with an argument that is a
+	path to the top-level source directory;
+
+	when CMake finishes, run make to build Wireshark.
+
+For example, to build Wireshark in a subdirectory of the top-level
+source directory, named "build", do, from the top-level source
+directory;
+
+	mkdir build
+	cd build
+	cmake ..
+	make
 
 If you upgrade the major release of macOS on which you are building
 Wireshark, we advise that, before you do any builds after the upgrade,
-you do, in the build directory:
+you remove the build directory and all its subdiretories, and repeat the
-
+above process, re-running CMake and rebuilding from scratch.
-    If you are building from a release tarball:
-	make distclean
-
-    If you are building from Git:
-	make maintainer-clean
-	./autogen.sh
-
-Then re-run the configure script and rebuild from scratch.
 
 On Snow Leopard (10.6) and later releases, if you are building on a
 machine with a 64-bit processor (with the exception of the early Intel