Set language explicitly for .asm files, because otherwise macOS fails

Author: pdimov

CMakeLists.txt

@@ -125,8 +125,13 @@ if(BOOST_CONTEXT_IMPLEMENTATION STREQUAL "fcontext")
 
   set(IMPL_SOURCES ${ASM_SOURCES})
 
-  if(BOOST_CONTEXT_ASSEMBLER STREQUAL masm AND BOOST_CONTEXT_ARCHITECTURE STREQUAL i386)
-    set_source_files_properties(${ASM_SOURCES} PROPERTIES COMPILE_FLAGS "/safeseh")
+  if(BOOST_CONTEXT_ASSEMBLER STREQUAL masm)
+    set_source_files_properties(${ASM_SOURCES} PROPERTIES LANGUAGE "ASM_MASM")
+    if(BOOST_CONTEXT_ARCHITECTURE STREQUAL i386)
+      set_source_files_properties(${ASM_SOURCES} PROPERTIES COMPILE_FLAGS "/safeseh")
+    endif()
+  elseif(BOOST_CONTEXT_ASSEMBLER STREQUAL gas)
+    set_source_files_properties(${ASM_SOURCES} PROPERTIES LANGUAGE "ASM-ATT")
   endif()
 
 else()