Add test configs for MUSL C library.

.github/configs

@@ -67,6 +67,12 @@ case "$config" in
     libedit)
 	CONFIGFLAGS="--with-libedit"
 	;;
+    musl)
+	CC="musl-gcc"
+	CONFIGFLAGS="--without-zlib"
+	LIBCRYPTOFLAGS="--without-openssl"
+	TEST_TARGET="t-exec"
+	;;
     pam-krb5)
 	CONFIGFLAGS="--with-pam --with-kerberos5"
 	SSHD_CONFOPTS="UsePam yes"

.github/setup_ci.sh

@@ -57,6 +57,9 @@ for TARGET in $TARGETS; do
     hardenedmalloc)
         INSTALL_HARDENED_MALLOC=yes
         ;;
+    musl)
+	PACKAGES="$PACKAGES musl-tools"
+	;;
     tcmalloc)
         PACKAGES="$PACKAGES libgoogle-perftools-dev"
         ;;

.github/workflows/c-cpp.yml

@@ -38,6 +38,7 @@ jobs:
           - { os: ubuntu-20.04, configs: kitchensink }
           - { os: ubuntu-20.04, configs: hardenedmalloc }
           - { os: ubuntu-20.04, configs: tcmalloc }
+          - { os: ubuntu-20.04, configs: musl }
           - { os: ubuntu-latest, configs: libressl-master }
           - { os: ubuntu-latest, configs: libressl-2.2.9 }
           - { os: ubuntu-latest, configs: libressl-2.8.3 }