Change Linux build script to recognize more supported distributions

This changes the way the Linux build script recognizes which
distribution script might be compatible with the host OS.  It
does so by checking both the `ID` and `ID_LIKE` tags in
`/etc/os-release` against available scripts in `linux.d`.  First match
is used.

Note that ID_LIKE isn't a 100% compatability guarantee, but it gives the
user a fighting chance that the script will work for their distribution,
and should reduce the need for manual addition of more distribution
targets.

BuildLinux.sh

@@ -84,17 +84,26 @@ fi
 
 DISTRIBUTION=$(awk -F= '/^ID=/ {print $2}' /etc/os-release)
 VERSION=$(awk -F= '/^VERSION_ID=/ {print $2}' /etc/os-release)
-# treat ubuntu as debian
-if [ "${DISTRIBUTION}" == "ubuntu" ]
-then
-    DISTRIBUTION="debian"
-fi
-if [ ! -f ./linux.d/${DISTRIBUTION} ]
+# OSLIKE is a space-delineated list of similar distributions
+OSLIKE=$(awk -F= '/^ID_LIKE=/ {print $2}' /etc/os-release | tr -d '"')
+
+# Iterate over a list of candidate distribution targets, first match is used
+for CANDIDATE in ${DISTRIBUTION} ${OSLIKE}; do
+    if [ -f ./linux.d/${CANDIDATE} ]
+    then 
+        TARGET_DISTRO="${CANDIDATE}"
+        break
+    fi
+done
+
+if [ -z ${TARGET_DISTRO} ]
 then
     echo "Your distribution does not appear to be currently supported by these build scripts"
     exit 1
 fi
-source ./linux.d/${DISTRIBUTION}
+
+echo "OS distribution is '${DISTRIBUTION}'.  Using package dependencies for '${TARGET_DISTRO}'."
+source ./linux.d/${TARGET_DISTRO}
 
 echo "FOUND_GTK3=${FOUND_GTK3}"
 if [[ -z "${FOUND_GTK3_DEV}" ]]
@@ -196,4 +205,4 @@ echo "[9/9] Generating Linux app..."
         fi
     popd
 echo "done"
-fi
+fi