mesalink: remove support

Mesalink has ceased development. We can no longer encourage use of it.
It seems to be continued under the name TabbySSL, but no attempts have
(yet) been to make curl support it.

Fixes #8188
Closes #8191

scripts/zuul/before_script.sh

@@ -125,23 +125,6 @@ fi
 # Install common libraries.
 if [ $TRAVIS_OS_NAME = linux ]; then
 
-  if [ "$MESALINK" = "yes" ]; then
-    if [ ! -e $HOME/mesalink-1.0.0/Makefile ]; then
-      cd $HOME
-      curl https://sh.rustup.rs -sSf | sh -s -- -y
-      source $HOME/.cargo/env
-      curl -LO https://github.com/mesalock-linux/mesalink/archive/v1.0.0.tar.gz
-      tar -xzf v1.0.0.tar.gz
-      cd mesalink-1.0.0
-      ./autogen.sh
-      ./configure --enable-tls13
-      make
-    fi
-    cd $HOME/mesalink-1.0.0
-    sudo make install
-
-  fi
-
   if [ "$BEARSSL" = "yes" ]; then
     if [ ! -e $HOME/bearssl-0.6/Makefile ]; then
       cd $HOME

scripts/zuul/script.sh

@@ -58,12 +58,6 @@ if [ "$T" = "debug" ]; then
   fi
 fi
 
-if [ "$T" = "debug-mesalink" ]; then
-  ./configure --enable-debug --enable-werror $C
-  make
-  make "TFLAGS=-n !313 !410 !3001" test-nonflaky
-fi
-
 if [ "$T" = "debug-bearssl" ]; then
   ./configure --enable-debug --enable-werror $C
   make