macos-setup: more cleanups.

Fix/update/expand some comments.

Do uninstalls for dependencies using CMake more similarly.

For LZ4, as it comes with a Makefile rather than any
autotools/CMake/etc. configuration, "make distclean" might not be
necessary, so, as it's not supported, just do "make clean".

For libssh, do all removes in the uninstall in a single command, and use
$DO_RM, so that it uses sudo iff /usr/local isn't writable by us.  In
addition, remove the build directory as the equivalent of "make
distclean".

As with libssh, so with brotli.

(backported from commit 02c5f50009)

tools/macos-setup.sh

@@ -60,7 +60,8 @@ XZ_VERSION=5.2.3
 LZIP_VERSION=1.19
 
 #
-# CMake is required to do the build.
+# CMake is required to do the build - and to build some of the
+# dependencies.
 #
 # Sigh.  CMake versions 3.7 and later fail on Lion due to issues with
 # Lion's libc++, and CMake 3.5 and 3.6 have an annoying "Make sure the
@@ -1372,9 +1373,12 @@ uninstall_lz4() {
         cd lz4-$installed_lz4_version
         $DO_MAKE_UNINSTALL || exit 1
         #
-        # lz4 uses cmake and doesn't support "make distclean"
+        # lz4's Makefile doesn't support "make distclean"; just do
+        # "make clean".  Perhaps not using autotools means that
+        # there's no need for "make distclean".
         #
         # make distclean || exit 1
+        make clean || exit 1
         cd ..
         rm lz4-$installed_lz4_version-done
 
@@ -1529,17 +1533,20 @@ uninstall_libssh() {
         echo "Uninstalling libssh:"
         cd libssh-$installed_libssh_version
         #
-        # libssh uses cmake and doesn't support "make uninstall"
+        # libssh uses cmake and doesn't support "make uninstall";
+        # just remove what we know it installs.
         #
         # $DO_MAKE_UNINSTALL || exit 1
-        sudo rm -rf /usr/local/lib/libssh*
-        sudo rm -rf /usr/local/include/libssh
-        sudo rm -rf /usr/local/lib/pkgconfig/libssh*
-        sudo rm -rf /usr/local/lib/cmake/libssh
+        $DO_RM -rf /usr/local/lib/libssh* \
+                   /usr/local/include/libssh \
+                   /usr/local/lib/pkgconfig/libssh* \
+                   /usr/local/lib/cmake/libssh || exit 1
         #
-        # libssh uses cmake and doesn't support "make distclean"
+        # libssh uses cmake and doesn't support "make distclean";
+        # just remove the entire build directory.
         #
         # make distclean || exit 1
+        rm -rf build || exit 1
         cd ..
         rm libssh-$installed_libssh_version-done
 
@@ -1885,17 +1892,20 @@ uninstall_brotli() {
         echo "Uninstalling brotli:"
         cd brotli-$installed_brotli_version
         #
-        # brotli uses cmake on macOS and doesn't support "make uninstall"
+        # brotli uses cmake on macOS and doesn't support "make uninstall";
+        # just remove what we know it installs.
         #
         # $DO_MAKE_UNINSTALL || exit 1
-        sudo rm -rf /usr/local/bin/brotli
-        sudo rm -rf /usr/local/lib/libbrotli*
-        sudo rm -rf /usr/local/include/brotli
-        sudo rm -rf /usr/local/lib/pkgconfig/libbrotli*
+        $DO_RM -rf /usr/local/bin/brotli \
+                   /usr/local/lib/libbrotli* \
+                   /usr/local/include/brotli \
+                   /usr/local/lib/pkgconfig/libbrotli* || exit 1
         #
-        # brotli uses cmake on macOS and doesn't support "make distclean"
+        # brotli uses cmake on macOS and doesn't support "make distclean";
+        # just remove the enire build directory.
         #
         # make distclean || exit 1
+        rm -rf build_dir || exit 1
         cd ..
         rm brotli-$installed_brotli_version-done