Remove references to ARM-optimized math implementation

The necessary header files do not exist in the repository.

This is an alternative to https://gn-review.googlesource.com/c/gn/+/3440.

Bug: https://bugs.gentoo.org/672862
Change-Id: I629ae109c98661ee5b4b83e67ce7c1545b112772
Reviewed-on: https://gn-review.googlesource.com/c/4040
Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Scott Graham <scottmg@chromium.org>

base/numerics/safe_conversions.h

diff --git a/base/numerics/safe_conversions.h b/base/numerics/safe_conversions.h
index a4fe387..71d6e61 100644
--- a/base/numerics/safe_conversions.h
+++ b/base/numerics/safe_conversions.h
@@ -13,12 +13,7 @@
 
 #include "base/numerics/safe_conversions_impl.h"
 
-#if !defined(__native_client__) && (defined(__ARMEL__) || defined(__arch64__))
-#include "base/numerics/safe_conversions_arm_impl.h"
-#define BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS (1)
-#else
 #define BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS (0)
-#endif
 
 namespace base {
 namespace internal {

base/numerics/safe_math_clang_gcc_impl.h

diff --git a/base/numerics/safe_math_clang_gcc_impl.h b/base/numerics/safe_math_clang_gcc_impl.h
index 1760338..660a57f 100644
--- a/base/numerics/safe_math_clang_gcc_impl.h
+++ b/base/numerics/safe_math_clang_gcc_impl.h
@@ -11,12 +11,7 @@
 
 #include "base/numerics/safe_conversions.h"
 
-#if !defined(__native_client__) && (defined(__ARMEL__) || defined(__arch64__))
-#include "base/numerics/safe_math_arm_impl.h"
-#define BASE_HAS_ASSEMBLER_SAFE_MATH (1)
-#else
 #define BASE_HAS_ASSEMBLER_SAFE_MATH (0)
-#endif
 
 namespace base {
 namespace internal {