CI: enable parallel make in more builds

Most CI services provide at least two cores, so enable parallel make
jobs to take advantage of that for builds. Some dependencies aren't safe
to build in parallel so leave those as-is.  Also, rename a few
workflows to eliminate duplicate names and provide a better idea what
they're about.

.github/workflows/linux.yml

@@ -39,6 +39,9 @@ concurrency:
 
 permissions: {}
 
+env:
+  MAKEFLAGS: -j 3
+
 jobs:
   autotools:
     name: ${{ matrix.build.name }}
@@ -231,7 +234,7 @@ jobs:
         git clone --quiet --depth=1 https://github.com/openssl/openssl
         cd openssl
         ./config enable-tls1_3 --prefix=$HOME/openssl3
-        make install_sw
+        make -j1 install_sw
       name: 'install openssl'
 
     - if: ${{ contains(matrix.build.install_steps, 'quictls') }}
@@ -239,7 +242,7 @@ jobs:
         git clone --quiet --depth=1 -b OpenSSL_1_1_1t+quic https://github.com/quictls/openssl
         cd openssl
         ./config enable-tls1_3 --prefix=$HOME/quictls
-        make install_sw
+        make -j1 install_sw
       name: 'install quictls'
 
     - if: ${{ contains(matrix.build.install_steps, 'msh3') }}