cmake: update SetHwArchString()

The patch simplifies the implementation of the function
`SetHwArchString()` for obtaining the architecture name.
Needed for the following patch with macOS support and Ubuntu 24.04
AArch64 (ARM64) support.

Needed for #59

Author: ligurio

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Support Address and UndefinedBehaviour sanitizers.
 - Support LuaJIT metrics.
 - Support OSS Fuzz environment (#73).
+- Support for building on Ubuntu 24.04 AArch64 (ARM64).
 
 ### Changed
 

cmake/SetClangRTLib.cmake

@@ -1,12 +1,9 @@
+# The function sets the given variable in a parent scope to a
+# string with hardware architecture name and this name should
+# match to hardware architecture name used in a library name of
+# libclang_rt.fuzzer_no_main: aarch64, x86_64, i386.
 function(SetHwArchString outvar)
-  if (CMAKE_SIZEOF_VOID_P EQUAL 4)
-    set(hw_arch "i386")
-  elseif (CMAKE_SIZEOF_VOID_P EQUAL 8)
-    set(hw_arch "x86_64")
-  else ()
-    message(FATAL_ERROR "Unsupported architecture.")
-  endif ()
-  set(${outvar} ${hw_arch} PARENT_SCOPE)
+  set(${outvar} ${CMAKE_SYSTEM_PROCESSOR} PARENT_SCOPE)
 endfunction()
 
 # The function sets the given variable in a parent scope to a