build: allow unbundling of Node.js dependencies

Author: codebytere

node.gni

@@ -62,6 +62,12 @@ declare_args() {
 
   # Build with Amaro (TypeScript utils).
   node_use_amaro = true
+
+  # Allows downstream packagers (eg. Linux distributions) to build against system shared libraries.
+  use_system_cares = false
+  use_system_nghttp2 = false
+  use_system_llhttp = false
+  use_system_histogram = false
 }
 
 assert(!node_enable_inspector || node_use_openssl,

unofficial.gni

@@ -153,7 +153,6 @@ template("node_gn_build") {
       "deps/brotli",
       "deps/cares",
       "deps/histogram",
-      "deps/llhttp",
       "deps/nbytes",
       "deps/nghttp2",
       "deps/ngtcp2",
@@ -179,7 +178,17 @@ template("node_gn_build") {
       configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
       configs += [ "//build/config/gcc:symbol_visibility_default" ]
     }
-
+    if (use_system_llhttp) {
+      libs += [ "llhttp" ]
+    } else {
+      deps += [ "deps/llhttp" ]
+    }
+    if (use_system_histogram) {
+      libs += [ "hdr_histogram" ]
+      include_dirs += [ "/usr/include/hdr" ]
+    } else {
+      deps += [ "deps/histogram" ]
+    }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
@@ -206,6 +215,19 @@ template("node_gn_build") {
       sources += node_inspector.node_inspector_sources +
                  node_inspector.node_inspector_generated_sources
     }
+    if (is_linux) {
+      import("//build/config/linux/pkg_config.gni")
+        if (use_system_cares) {
+          pkg_config("cares") {
+            packages = [ "libcares" ]
+          }
+        }
+      if (use_system_nghttp2) {
+        pkg_config("nghttp2") {
+          packages = [ "libnghttp2" ]
+        }
+      }
+    }
   }
 
   executable(target_name) {