Revert "[BitCode] decode nossp fn attr"

This reverts commit 0b11d01.

Going with a simpler approach.

Author: nickdesaulniers

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -1537,8 +1537,6 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::ByRef;
   case bitc::ATTR_KIND_MUSTPROGRESS:
     return Attribute::MustProgress;
-  case bitc::ATTR_KIND_NO_STACK_PROTECT:
-    return Attribute::NoStackProtect;
   }
 }
 

llvm/test/Bitcode/attributes.ll

@@ -404,12 +404,6 @@ define void @f68() mustprogress
   ret void
 }
 
-; CHECK; define void @f69() #42
-define void @f69() nossp
-{
-  ret void
-}
-
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { readnone }
@@ -452,5 +446,4 @@ define void @f69() nossp
 ; CHECK: attributes #39 = { sanitize_memtag }
 ; CHECK: attributes #40 = { null_pointer_is_valid }
 ; CHECK: attributes #41 = { mustprogress }
-; CHECK: attributes #42 = { nossp }
 ; CHECK: attributes #[[NOBUILTIN]] = { nobuiltin }