Merge pull request #16 from eisenhauer/LibFFIOnUnsupp

Try to build libffi when not found on unsupported architectures

CMakeLists.txt

@@ -143,10 +143,11 @@ find_package(LibFFI)
 if(LIBFFI_FOUND)
   message(STATUS "Enabling emulation")
   set(EMULATION_POSSIBLE TRUE)
-elseif(DILL_IGNORE_NATIVE)
+elseif(DILL_IGNORE_NATIVE OR (NATIVE_ARCH STREQUAL "UNSUPPORTED"))
   find_program (AUTOCONF autoconf)
-  if (AUTOCONF STREQUAL "AUTOCONF-NOTFOUND")
-      message(FATAL_ERROR "DILL_IGNORE_NATIVE set, but autoconf not found, so unable to build libffi")
+  find_program (AUTOMAKE automake)
+  if ((AUTOCONF STREQUAL "AUTOCONF-NOTFOUND") OR (AUTOMAKE STREQUAL "AUTOMAKE-NOTFOUND"))
+      message(FATAL_ERROR "DILL_IGNORE_NATIVE set or native architecture unsupported, but autoconf or automake not found, so unable to build libffi")
   endif()
   set(LIBFFI_INTERNAL ON)
   message(STATUS "Using private copy of libffi")