AsmParser: Don't crash on short hex constants for fp128 types

If we see 0xL01, treat it like 0xL00000000000000000000000000000001
instead of crashing.

llvm-svn: 223811
diff --git a/llvm/test/Assembler/short-hexpair.ll b/llvm/test/Assembler/short-hexpair.ll
new file mode 100644
index 0000000..067ea30
--- /dev/null
+++ b/llvm/test/Assembler/short-hexpair.ll
@@ -0,0 +1,4 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+
+@x = global fp128 0xL01
+; CHECK: @x = global fp128 0xL00000000000000000000000000000001