Mark assembly files as SafeSEH compatible

These assembly files contain no exception handlers, so we can just emit
the special @feat.00 symbol to indicate that they're trivially SafeSEH
compatible. See [1] for details.

[1] https://msdn.microsoft.com/en-us/library/windows/desktop/ms680547(v=vs.85).aspx#the_.sxdata_section_

Author: smeenai

CoreFoundation/Base.subproj/CFAsmMacros.h

@@ -20,5 +20,16 @@
 #define NO_EXEC_STACK_DIRECTIVE
 #endif
 
+.macro SAFESEH_REGISTRATION_DIRECTIVE
+#if defined(_WIN32) && defined(_M_IX86)
+    .def @feat.00
+        .scl 3
+        .type 0
+    .endef
+    .globl @feat.00
+@feat.00 = 1
+#endif
+.endm
+
 #endif
 

CoreFoundation/String.subproj/CFCharacterSetData.S

@@ -22,4 +22,4 @@ _C_LABEL(__CFCharacterSetBitmapDataSize):
     .int _C_LABEL(__CFCharacterSetBitmapDataEnd) - _C_LABEL(__CFCharacterSetBitmapData)
 
 NO_EXEC_STACK_DIRECTIVE
-
+SAFESEH_REGISTRATION_DIRECTIVE

CoreFoundation/String.subproj/CFUniCharPropertyDatabase.S

@@ -22,4 +22,4 @@ _C_LABEL(__CFUniCharPropertyDatabaseSize):
     .int _C_LABEL(__CFUniCharPropertyDatabaseEnd) - _C_LABEL(__CFUniCharPropertyDatabase)
 
 NO_EXEC_STACK_DIRECTIVE
-
+SAFESEH_REGISTRATION_DIRECTIVE

CoreFoundation/String.subproj/CFUnicodeData.S

@@ -36,4 +36,4 @@ _C_LABEL(__CFUnicodeDataLSize):
 #endif
 
 NO_EXEC_STACK_DIRECTIVE
-
+SAFESEH_REGISTRATION_DIRECTIVE