Don't build with -mcpu= on aarch64

Index: lib/common/CMakeLists.txt
--- lib/common/CMakeLists.txt.orig
+++ lib/common/CMakeLists.txt
@@ -132,8 +132,6 @@ elseif(${LIBPGMATH_SYSTEM_PROCESSOR} MATCHES "ppc64le"
     sincosf.c)
 elseif(${LIBPGMATH_SYSTEM_PROCESSOR} MATCHES "aarch64")
   set_property(SOURCE dispatch.c APPEND_STRING PROPERTY COMPILE_FLAGS "-fno-builtin")
-  set_property(SOURCE mth_xintrinsics.c APPEND_STRING PROPERTY COMPILE_FLAGS "-mcpu=${LLVM_FLANG_CPU_TARGET} ")
-  set_property(SOURCE mth_128defs.c mth_128defs_init.c mth_128defs_stats.c APPEND_STRING PROPERTY COMPILE_FLAGS "-mcpu=${LLVM_FLANG_CPU_TARGET} ")
   set_property(SOURCE mth_128defs_init.c APPEND PROPERTY COMPILE_DEFINITIONS MTH_I_INTRIN_INIT)
   set_property(SOURCE mth_128defs_stats.c APPEND PROPERTY COMPILE_DEFINITIONS MTH_I_INTRIN_STATS)
   set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z -Wl,combreloc")
