home-manager: pass `-j` to nix-build

Fixes #1596

doc/man-home-manager.xml

@@ -115,7 +115,16 @@
    </arg>
     
    <arg>
-    --max-jobs <replaceable>number</replaceable>
+     <group choice="req">
+       <arg choice="plain">
+         -j
+       </arg>
+
+       <arg choice="plain">
+         --max-jobs
+       </arg>
+     </group>
+     <replaceable>number</replaceable>
    </arg>
     
    <arg>
@@ -417,6 +426,9 @@
     </listitem>
    </varlistentry>
    <varlistentry>
+    <term>
+     <option>-j <replaceable>number</replaceable></option>
+    </term>
     <term>
      <option>--max-jobs <replaceable>number</replaceable></option>
     </term>

home-manager/completion.bash

@@ -285,7 +285,8 @@ _home-manager_completions ()
     #--------------------------#
 
     local Options
-    Options=( "-f" "--file" "-b" "-A" "-I" "-h" "--help" "-n" "--dry-run" "-v" "--verbose" "--show-trace" )
+    Options=( "-f" "--file" "-b" "-A" "-I" "-h" "--help" "-n" "--dry-run" "-v" "--verbose" "--show-trace" \
+              "-j" "--max-jobs" )
 
     # ^ « home-manager »'s options.
 

home-manager/home-manager

@@ -424,7 +424,7 @@ function doHelp() {
     echo "  --cores NUM"
     echo "  --keep-failed"
     echo "  --keep-going"
-    echo "  --max-jobs NUM"
+    echo "  -j, --max-jobs NUM"
     echo "  --option NAME VALUE"
     echo "  --show-trace"
     echo "  --(no-)substitute"
@@ -501,7 +501,7 @@ while [[ $# -gt 0 ]]; do
             PASSTHROUGH_OPTS+=("$opt" "$1" "$2")
             shift 2
             ;;
-        --max-jobs|--cores)
+        -j|--max-jobs|--cores)
             PASSTHROUGH_OPTS+=("$opt" "$1")
             shift
             ;;