IRGen: Use the correct triple when checking for YAML legacy type info

IGM.Triple is irgen.getEffectiveClangTriple(), which says "thumbv7"
in place of "armv7" for 32-bit iOS ARM targets.

Instead, lets use IGM.Context.LangOpts.Target, which is what we use
to find swiftmodule files.

Author: slavapestov

lib/IRGen/GenType.cpp

@@ -1151,6 +1151,8 @@ TypeConverter::TypeConverter(IRGenModule &IGM)
   if (IGM.IRGen.Opts.EnableResilienceBypass)
     LoweringMode = Mode::CompletelyFragile;
 
+  const auto &Triple = IGM.Context.LangOpts.Target;
+
   // We have a bunch of -parse-stdlib tests that pass a -target in the test
   // suite. To prevent these from failing when the user hasn't build the
   // standard library for that target, we pass -disable-legacy-type-info to
@@ -1165,8 +1167,8 @@ TypeConverter::TypeConverter(IRGenModule &IGM)
     // If the flag was not explicitly specified, look for a file in a
     // platform-specific location, if this platform is known to require
     // one.
-    auto platformName = getPlatformNameForTriple(IGM.Triple);
-    auto archName = getMajorArchitectureName(IGM.Triple);
+    auto platformName = getPlatformNameForTriple(Triple);
+    auto archName = swift::getMajorArchitectureName(Triple);
 
     if (!doesPlatformUseLegacyLayouts(platformName, archName))
       return;

test/IRGen/arm_to_thumb_darwin.sil

@@ -1,5 +1,5 @@
-// RUN: %swift -target armv7-apple-ios7 %s -gnone -emit-ir -o - | %FileCheck %s -check-prefix=IOS
-// RUN: %swift -target armv7k-apple-watchos2 %s -gnone -emit-ir -o - | %FileCheck %s -check-prefix=WATCHOS
+// RUN: %swift -target armv7-apple-ios7 -disable-legacy-type-info %s -gnone -emit-ir -o - | %FileCheck %s -check-prefix=IOS
+// RUN: %swift -target armv7k-apple-watchos2 -disable-legacy-type-info %s -gnone -emit-ir -o - | %FileCheck %s -check-prefix=WATCHOS
 
 // REQUIRES: CODEGENERATOR=ARM
 

test/IRGen/autorelease_optimized_armv7.sil

@@ -1,4 +1,4 @@
-// RUN: %swift -gnone -O -target armv7-apple-ios7 -emit-assembly %s -o - | %FileCheck %s
+// RUN: %swift -gnone -O -target armv7-apple-ios7 -disable-legacy-type-info -emit-assembly %s -o - | %FileCheck %s
 
 // REQUIRES: CODEGENERATOR=ARM
 

test/IRGen/bridge_object_armv7.sil

@@ -1,4 +1,4 @@
-// RUN: %swift -module-name bridge_object -emit-ir -target armv7-apple-ios8.0 %s | %FileCheck %s
+// RUN: %swift -module-name bridge_object -emit-ir -target armv7-apple-ios8.0 -disable-legacy-type-info %s | %FileCheck %s
 
 // REQUIRES: CODEGENERATOR=ARM
 

test/IRGen/integer_literal.sil

@@ -1,4 +1,4 @@
-// RUN: %swift -target armv7-apple-ios10 -module-name integer_literal %s -gnone -emit-ir | %FileCheck %s
+// RUN: %swift -target armv7-apple-ios10 -disable-legacy-type-info -module-name integer_literal %s -gnone -emit-ir | %FileCheck %s
 
 // REQUIRES: CODEGENERATOR=ARM
 

test/IRGen/ordering_arm.sil

@@ -1,4 +1,4 @@
-// RUN: %swift -target armv7-apple-ios7.1 %s -module-name main -emit-ir -o - | %FileCheck %s
+// RUN: %swift -target armv7-apple-ios7.1 -disable-legacy-type-info %s -module-name main -emit-ir -o - | %FileCheck %s
 
 // REQUIRES: CODEGENERATOR=ARM