[Verifier] remove stale comment about PHI with no operands; NFC

The code was changed with:
9eb2c0113dfe
...but missed the corresponding code comment.

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 2e208a0..3c617d2 100644 (file)
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -23,7 +23,6 @@
 //  * Only phi nodes can be self referential: 'add i32 %0, %0 ; <int>:0' is bad
 //  * PHI nodes must have an entry for each predecessor, with no extras.
 //  * PHI nodes must be the first thing in a basic block, all grouped together
-//  * PHI nodes must have at least one entry
 //  * All basic blocks should only end with terminator insts, not contain them
 //  * The entry node to a function must not have predecessors
 //  * All Instructions must be embedded into a basic block