Pin the reflection data sections on Linux

These had similar problems to the protocol conformance sections during
Linux bringup. There are relative offsets from the main reflection
section to the two string sections, so their position relative to each
other must remain fixed.

Author: bitjammer

stdlib/public/runtime/swift.ld

@@ -1,5 +1,8 @@
 SECTIONS
 {
+  .swift3_typeref : { *(.swift3_typeref) },
+  .swift3_reflstr : { *(.swift3_reflstr) },
+  .swift3_reflect : { *(.swift3_reflect) },
   .swift2_protocol_conformances :
   {
     .swift2_protocol_conformances_start = . ;