[LLVMContextImpl] Separate out integer constant ones

Very small compile time improvement:
https://llvm-compile-time-tracker.com/compare.php?from=6a7a8907e8334eaf551742148079c628f78e6ed7&to=454d1181fbdb9121f0c7a3ecf526520db32ab420&stat=instructions:u

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D144746
diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 98157e6..c076ee0 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -117,6 +117,7 @@
   UVConstants.clear();
   PVConstants.clear();
   IntZeroConstants.clear();
+  IntOneConstants.clear();
   IntConstants.clear();
   FPConstants.clear();
   CDSConstants.clear();