build: Reduce link concurrency for sanitizer coverage builds.

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 afce336781c15d18065a58cee511594fd066663d..d97a680957a355e0ff49706da6b080e1a05dad04 100644
--- a/build/toolchain/concurrent_links.gni
+++ b/build/toolchain/concurrent_links.gni
@@ -33,6 +33,10 @@ if (concurrent_links == -1) {
         "--reserve_mem_gb=20",
       ]
     }
+  } else if (use_sanitizer_coverage) {
+    # Sanitizer coverage instrumentation increases linker memory consumption
+    # significantly.
+    _args = [ "--mem_per_link_gb=12" ]
   } else if (is_win) {
     _args = [ "--mem_per_link_gb=5" ]
   } else if (is_mac) {