Set cmake flags based on selected processor (#60)

* Use selected processor for setting march

This allows for cross compilation without setting the `-march=native`.

* Pass CMAKE_SYSTEM_PROCESSOR through superbuild

* Additional superbuild flag passing

Author: Shelnutt2

src/CMakeLists.txt

@@ -93,12 +93,12 @@ enable_testing()
 # Build types and default flags
 # -----------------------------------------------------------------------------
 
-message("Architecture is ${CMAKE_HOST_SYSTEM_PROCESSOR}")
+message("Architecture is ${CMAKE_SYSTEM_PROCESSOR}")
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
     set(FCONCEPTS_DIAGNOSTICS_DEPTH "-fconcepts-diagnostics-depth=3")
 endif()
 
-if (CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL arm64)
+if (CMAKE_OSX_ARCHITECTURES STREQUAL arm64 OR CMAKE_SYSTEM_PROCESSOR MATCHES "^aarch64" OR CMAKE_SYSTEM_PROCESSOR MATCHES "^arm")
     set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g -fno-elide-constructors ${FCONCEPTS_DIAGNOSTICS_DEPTH} " CACHE STRING "" FORCE)
     set(CMAKE_CXX_FLAGS_RELEASE "-Ofast -DNDEBUG " CACHE STRING "" FORCE)
     set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-Ofast -g -DNDEBUG" CACHE STRING "" FORCE)

src/cmake/Superbuild.cmake

@@ -49,6 +49,13 @@ set(INHERITED_CMAKE_ARGS
   -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
   -DCMAKE_PREFIX_PATH=${CMAKE_PREFIX_PATH}
   -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+  -DCMAKE_SYSTEM_PROCESSOR=${CMAKE_SYSTEM_PROCESSOR}
+  -DCMAKE_OSX_ARCHITECTURES=${CMAKE_OSX_ARCHITECTURES}
+  -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+  -DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}
+  -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+  -DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}
+  -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
   -DEP_BASE=${EP_BASE}
   -DFORCE_EXTERNAL_TILEDB=${FORCE_EXTERNAL_TILEDB}
   -DTILEDB_S3=${TILEDB_S3}