[NFC][msan] Fix typo in comment

Author: vitalybuka

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

@@ -5109,7 +5109,7 @@ struct VarArgAArch64Helper : public VarArgHelper {
   // like x86_64 case, lowers the va_args in the frontend and this pass only
   // sees the low level code that deals with va_list internals).
   // The first seven GR registers are saved in the first 56 bytes of the
-  // va_arg tls arra, followers by the first 8 FP/SIMD registers, and then
+  // va_arg tls arra, followed by the first 8 FP/SIMD registers, and then
   // the remaining arguments.
   // Using constant offset within the va_arg TLS array allows fast copy
   // in the finalize instrumentation.