cmake : only enable GGML_NATIVE and x86 flags if not crosscompiling (ggml/885)

ggml/CMakeLists.txt

@@ -50,9 +50,15 @@ else()
     set(GGML_BLAS_VENDOR_DEFAULT "Generic")
 endif()
 
+if (CMAKE_CROSSCOMPILING)
+    set(GGML_NATIVE_DEFAULT OFF)
+else()
+    set(GGML_NATIVE_DEFAULT ON)
+endif()
+
 # general
 option(GGML_STATIC "ggml: static link libraries"         OFF)
-option(GGML_NATIVE "ggml: enable -march=native flag"     ON)
+option(GGML_NATIVE "ggml: enable -march=native flag"     ${GGML_NATIVE_DEFAULT})
 option(GGML_LTO    "ggml: enable link time optimization" OFF)
 option(GGML_CCACHE "ggml: use ccache if available"       ON)
 
@@ -70,7 +76,7 @@ option(GGML_SANITIZE_ADDRESS   "ggml: enable address sanitizer"   OFF)
 option(GGML_SANITIZE_UNDEFINED "ggml: enable undefined sanitizer" OFF)
 
 # instruction set specific
-if (GGML_NATIVE)
+if (GGML_NATIVE OR NOT GGML_NATIVE_DEFAULT)
     set(INS_ENB OFF)
 else()
     set(INS_ENB ON)