[config] Suppress implicit fallthrough

Change-Id: I19d3a7de3323d682ce1d343bcad440f3626360e1

BUILD.gn

diff --git a/BUILD.gn b/BUILD.gn
index 5b9bb92..9518ae9 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -150,10 +150,12 @@
   }
 
   cflags = [
-    "-Wno-sign-compare",
-    "-Wno-format",
-    "-Wno-parentheses-equality",
     "-Wno-address-of-packed-member",
+    "-Wno-conversion",
+    "-Wno-format",
+    "-Wno-implicit-fallthrough",
+    "-Wno-parentheses-equality",
+    "-Wno-sign-compare",
     "-Wno-unused-function",
   ]
   if (current_cpu == "arm64") {
@@ -262,8 +264,6 @@
   # TODO(44349): UBSan has found an instance of undefined behavior in this target.
   # Disable UBSan for this target temporarily until it is migrated into CI/CQ.
   configs += [ "//build/config:temporarily_disable_ubsan_do_not_use" ]
-  # TODO(fxb/58162): delete the below and fix compiler warnings
-  configs += [ "//build/config:Wno-conversion" ]
 }
 
 source_set("src_no_hardware") {
@@ -290,8 +290,6 @@
   # TODO(44349): UBSan has found an instance of undefined behavior in this target.
   # Disable UBSan for this target temporarily until it is migrated into CI/CQ.
   configs += [ "//build/config:temporarily_disable_ubsan_do_not_use" ]
-  # TODO(fxb/58162): delete the below and fix compiler warnings
-  configs += [ "//build/config:Wno-conversion" ]
 }
 
 source_set("unit_tests") {