openblas: try to workaround a compiler crash by building with -Os

-O1 and -Os seem to work here, but the later is easier to set via the
build type.

mingw-w64-openblas/PKGBUILD

@@ -66,11 +66,18 @@ prepare() {
 _build_openblas() {
   _idx_opt=$1
 
-  declare -a _build_type
+  declare _build_type
   if check_option "debug" "n"; then
-    _build_type+=("Release")
+    _build_type="Release"
   else
-    _build_type+=("Debug")
+    _build_type="Debug"
+  fi
+
+  # https://github.com/msys2/MINGW-packages/issues/13128
+  # MinSizeRel sets -Os, which seems to work around the compiler crash
+  # at least with the provided reproducer
+  if [[ ${MINGW_PACKAGE_PREFIX} == *-aarch64 ]]; then
+    _build_type="MinSizeRel"
   fi
 
   declare _c_lapack_opt