speedup macOS build

brew update is just dead slow on older travis images

.travis.yml

@@ -68,14 +68,21 @@ addons:
     - cmake
 
 before_install:
-  # brew install gengetopt help2man cmocka ccache llvm;
-  # export PATH="/usr/local/opt/ccache/libexec:/usr/local/opt/llvm/bin:$PATH";
-  # add magic notarization flags for macOS, see https://github.com/akeru-inc/xcnotary/blob/master/README.md
+  # homebrew is dead slow in older images due to the many updates it would need to download and build.
+  # here, we build the additional dependencies manually to get around this
   - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
-        brew update;
-        brew uninstall libtool;
-        brew install libtool;
-        brew install gengetopt help2man cmocka ccache git-lfs;
+        curl https://ftp.gnu.org/gnu/gengetopt/gengetopt-2.23.tar.xz -L --output gengetopt-2.23.tar.xz;
+        tar xfj gengetopt-2.23.tar.xz;
+        pushd gengetopt-2.23;
+        ./configure && make;
+        sudo make install;
+        popd;
+        curl https://ftp.gnu.org/gnu/help2man/help2man-1.47.16.tar.xz -L --output help2man-1.47.16.tar.xz;
+        tar xjf help2man-1.47.16.tar.xz;
+        pushd help2man-1.47.16;
+        ./configure && make;
+        sudo make install;
+        popd;
         export PATH="/usr/local/opt/ccache/libexec:$PATH";
         git clone https://github.com/frankmorgner/OpenSCToken.git;
     fi
@@ -352,15 +359,11 @@ after_script:
       rm -f .github/secrets.tar;
     fi
 
-before_cache:
-  - brew cleanup
-
 cache:
   apt: true
   ccache: true
   directories:
     - $HOME/.m2/
-    - $HOME/Library/Caches/Homebrew
     - openssl_bin
     - openpace_bin
     - isetup