[build] minor fixes

.github/workflows/check-md-links.yml

@@ -8,3 +8,5 @@ jobs:
     steps:
       - uses: actions/checkout@master
       - uses: gaurav-nelson/github-action-markdown-link-check@v1
+        with:
+          config-file: 'mlc_config.json'

.github/workflows/mlc_config.json

@@ -0,0 +1,10 @@
+{
+    "ignorePatterns": [
+        {
+            "pattern": "^/assets"
+        },
+        {
+            "pattern": "^https://archive.org"
+        }
+    ]
+}

src/Makefile.am

@@ -427,8 +427,10 @@ uncrusty:
 
 if !DISABLE_DOCUMENTATION
 all-local: lnav
-	env DUMP_INTERNALS_DIR=$(srcdir)/internals DUMP_CRASH=1 ./lnav Makefile
-	mv $(srcdir)/internals/*.schema.json $(top_srcdir)/docs/schemas
+	if test -w $(srcdir)/internals; then \
+		env DUMP_INTERNALS_DIR=$(srcdir)/internals DUMP_CRASH=1 ./lnav Makefile; \
+		mv $(srcdir)/internals/*.schema.json $(top_srcdir)/docs/schemas; \
+	fi
 endif
 
 install-exec-hook: