Drop the workaround for the third-party Android CMake toolchain.

When we first added Android support to the CMake build, we used a
third-party toolchain file, https://github.com/taka-no-me/android-cmake.
That project hasn't been updated since 2015 and, among other things,
doesn't support Armv8.

In 2017, we replaced it with the NDK's build-in toolchain file, which no
longer needed a particular workaround for ASM flags. See
https://boringssl-review.googlesource.com/c/boringssl/+/24165 and
https://boringssl-review.googlesource.com/c/boringssl/+/24164

Drop this workaround now.

Change-Id: I4af78d641b0c9b9608aaaa5ca31b9e80de024ab2
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/55627
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e643ece..1ebba93 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -513,13 +513,6 @@
   message(FATAL_ERROR "Unknown processor:" ${CMAKE_SYSTEM_PROCESSOR})
 endif()
 
-if(ANDROID AND NOT ANDROID_NDK_REVISION AND ARCH STREQUAL "arm")
-  # The third-party Android-NDK CMake files somehow fail to set the -march flag
-  # for assembly files. Without this flag, the compiler believes that it's
-  # building for ARMv5.
-  set(CMAKE_ASM_FLAGS "-march=${CMAKE_SYSTEM_PROCESSOR} ${CMAKE_ASM_FLAGS}")
-endif()
-
 if(USE_CUSTOM_LIBCXX)
   if(NOT CLANG)
     message(FATAL_ERROR "USE_CUSTOM_LIBCXX only supported with Clang")