[build] Add build options for uftrace support

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 30b5d5a57451790e53718e671926d677fd681daf..532ed2e3efa45eade0f79ff7bfcd2413df2e3658 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -69,6 +69,13 @@ declare_args() {
 
   # Similar to the ARM hard float ABI but on MIPS.
   v8_use_mips_abi_hardfloat = true
+
+  # Build with -pg option for gprof or uftrace
+  v8_pg_build = false
+
+  # Build with -finstrument-functions option for uftrace or general function
+  # instrumentation
+  v8_finstrument_build = false
 }
 
 # Set project-specific defaults for some args if not provided in args.gn. The
@@ -371,6 +378,20 @@ config("toolchain") {
     ]
   }
 
+  if (v8_pg_build) {
+    cflags += [
+      "-pg",
+      "-fno-omit-frame-pointer",
+    ]
+  }
+
+  if (v8_finstrument_build) {
+    cflags += [
+      "-finstrument-functions",
+      "-fno-omit-frame-pointer",
+    ]
+  }
+
   if (is_clang) {
     cflags += [
       "-Wsign-compare",