xo-cmake: + xo-build --build-docs

xo-cmake/bin/xo-build.in

@@ -27,6 +27,7 @@ Options:
   --configure       run cmake for xo library NAME in immediate subdir
                     Will use NAME/.build as build directory
   --build           run cmake build for xo library NAME in immediate subdir
+  --build-docs      build documentation for xo library NAME in immediate subdir
   --install         run cmake install for xo library NAME in immediate subdir
   -S=SOURCEDIR      override path/to/source
   -B=BUILDDIR       override path/to/build
@@ -86,6 +87,9 @@ while [[ $# > 0 ]]; do
         --build)
             build_flag=1
             ;;
+        --build-docs)
+            build_docs_flag=1
+            ;;
         --install)
             install_flag=1
             ;;
@@ -207,6 +211,18 @@ if [[ $build_flag -eq 1 ]]; then
     fi
 fi
 
+if [[ $build_docs_flag -eq 1 ]]; then
+    if [[ -n "$xoname" ]]; then
+        cmd="cmake --build $pathtobuild -- docs"
+
+        if [[ $noop_flag -eq 1 ]]; then
+            echo $cmd
+        else
+            $cmd
+        fi
+    fi
+fi
+
 if [[ $install_flag -eq 1 ]]; then
     if [[ -n "$xoname" ]]; then
         cmd="cmake --install $pathtobuild"