Get arch in this file (as utils.cmake is not included in UseBioDynaMo…

….cmake).

cmake/SetCompilerFlags.cmake

@@ -25,14 +25,17 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 # turn off compiler specific extensions e.g. gnu++17
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+# get machine architecture
+execute_process(COMMAND arch OUTPUT_VARIABLE DISTRO_ARCH OUTPUT_STRIP_TRAILING_WHITESPACE)
+
 # general flags
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wno-missing-braces -fPIC ${OpenMP_CXX_FLAGS}")
 set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS}   -Wall -Wno-missing-braces -fPIC ${OpenMP_C_FLAGS}")
-if(${DETECTED_ARCH} STREQUAL "x86_64")
+if(${DISTRO_ARCH} STREQUAL "x86_64")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m64")
     set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS}   -m64")
 endif()
-if(${DETECTED_ARCH} STREQUAL "aarch64")
+if(${DISTRO_ARCH} STREQUAL "aarch64")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mcpu=native")
     set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS}   -mcpu=native")
 endif()