Delete rtc_base/basictypes.h

Only remaining user was rtc_base/byteorder.h, which is changed to use
rtc_base/system/arch.h.

Bug: webrtc:6853
Change-Id: If3b21831adc60adfd989061027d661867c938a0f
Reviewed-on: https://webrtc-review.googlesource.com/78740
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23406}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 96822ca..b9cf3b9 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -104,7 +104,6 @@
 rtc_source_set("macromagic") {
   sources = [
     "arraysize.h",
-    "basictypes.h",
     "constructormagic.h",
     "format_macros.h",
     "stringize_macros.h",
@@ -385,6 +384,7 @@
     ":timeutils",
     ":type_traits",
     "../:typedefs",
+    "system:arch",
   ]
 
   sources = [
@@ -1104,7 +1104,6 @@
     sources = [
       "atomicops_unittest.cc",
       "base64_unittest.cc",
-      "basictypes_unittest.cc",
       "bind_unittest.cc",
       "bitbuffer_unittest.cc",
       "bitrateallocationstrategy_unittest.cc",