Frontend: address some late comments from Jordan

Move the option definition into FrontendOptions.td as it no longer can be passed
to the driver.  Use the single-dash separate form for the argument which is more
uniform with the rest of the options (and is arguably aesthetically more
pleasing).  NFC.

Author: compnerd

include/swift/Option/FrontendOptions.td

@@ -108,6 +108,9 @@ def print_clang_stats : Flag<["-"], "print-clang-stats">,
 def serialize_debugging_options : Flag<["-"], "serialize-debugging-options">,
   HelpText<"Always serialize options for debugging (default: only for apps)">;
 
+def autolink_library : Separate<["-"], "autolink-library">,
+  HelpText<"Add dependent library">, Flags<[FrontendOption]>;
+
 } // end let Flags = [FrontendOption, NoDriverOption]
 
 def debug_crash_Group : OptionGroup<"<automatic crashing options>">;

include/swift/Option/Options.td

@@ -272,9 +272,6 @@ def Xlinker : Separate<["-"], "Xlinker">,
   Flags<[DoesNotAffectIncrementalBuild]>,
   HelpText<"Specifies an option which should be passed to the linker">;
 
-def autolink_library : Joined<["-"], "autolink-library=">,
-  HelpText<"Add dependent library">, Flags<[FrontendOption]>;
-
 // Optimization levels
 
 def O_Group : OptionGroup<"<optimization level options>">;

test/IRGen/dependent-library.swift

@@ -1,4 +1,4 @@
-// RUN: %swift -target i686-unknown-windows-msvc -emit-ir -parse-as-library -parse-stdlib -module-name dependent -autolink-library=oldnames -autolink-library=msvcrt %s -o - | FileCheck %s
+// RUN: %swift -target i686-unknown-windows-msvc -emit-ir -parse-as-library -parse-stdlib -module-name dependent -autolink-library oldnames -autolink-library msvcrt %s -o - | FileCheck %s
 
 // CHECK: !{i32 6, !"Linker Options", ![[options:[0-9]+]]}
 // CHECK: ![[options]] = !{![[oldnames:[0-9]+]], ![[msvcrtd:[0-9]+]]}