Fix recently introduced typo.

Author: practicalswift

test/SILOptimizer/rcidentity.sil

@@ -56,7 +56,7 @@ enum E1 {
 // Tests //
 ///////////
 
-// Make sure that we see all the way through the chain of casts that %9 has an RCIdentity of %0 and that %12 is really the parial apply.
+// Make sure that we see all the way through the chain of casts that %9 has an RCIdentity of %0 and that %12 is really the partial apply.
 // CHECK-LABEL: @test_rcid_preserving_casts@
 // CHECK: RESULT #9: 9 = 0
 // CHECK: RESULT #12: 12 = 11