Propagate iquote appropriately from apple_binary so that generated headers of xctest apps are seen by ios_test

RELNOTES: None.
PiperOrigin-RevId: 153529262
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
index a028b09..0fce2f4 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
@@ -485,6 +485,7 @@
           HEADER,
           INCLUDE,
           INCLUDE_SYSTEM,
+          IQUOTE,
           LINKOPT,
           SDK_DYLIB,
           SDK_FRAMEWORK,