Increase link concurrency for ThinLTO.

build/toolchain/concurrent_links.gni

Index: build/toolchain/concurrent_links.gni
diff --git a/build/toolchain/concurrent_links.gni b/build/toolchain/concurrent_links.gni
index 163fc1b1aa97c32e99467fa5267065af6b3b2fcb..afce336781c15d18065a58cee511594fd066663d 100644
--- a/build/toolchain/concurrent_links.gni
+++ b/build/toolchain/concurrent_links.gni
@@ -21,10 +21,18 @@ declare_args() {
 
 if (concurrent_links == -1) {
   if (allow_posix_link_time_opt || is_cfi) {
-    _args = [
-      "--mem_per_link_gb=26",
-      "--reserve_mem_gb=20",
-    ]
+    if (use_thin_lto) {
+      _args = [
+        "--mem_per_link_gb=10",
+        "--reserve_mem_gb=10",
+      ]
+    } else {
+      # Full LTO, needs lots of RAM
+      _args = [
+        "--mem_per_link_gb=26",
+        "--reserve_mem_gb=20",
+      ]
+    }
   } else if (is_win) {
     _args = [ "--mem_per_link_gb=5" ]
   } else if (is_mac) {