Stop parsing into PoundDsohandleExprSyntax.

The general macro production works. We can't implement this as a macro just
yet, though.

Author: DougGregor

Sources/SwiftParser/Expressions.swift

@@ -1059,12 +1059,6 @@ extension Parser {
         poundColumn: tok,
         arena: self.arena
       ))
-    case (.poundDsohandleKeyword, let handle)?:
-      let tok = self.eat(handle)
-      return RawExprSyntax(RawPoundDsohandleExprSyntax(
-        poundDsohandle: tok,
-        arena: self.arena
-      ))
     case (.__dso_handle__Keyword, let handle)?:
       let tok = self.eat(handle)
       return RawExprSyntax(RawPoundDsohandleExprSyntax(

Sources/SwiftParser/Lexer.swift

@@ -1544,7 +1544,6 @@ extension Lexer.Cursor {
     case "fileID": kind = .poundFileIDKeyword
     case "filePath": kind = .poundFilePathKeyword
     case "function": kind = .poundFunctionKeyword
-    case "dsohandle": kind = .poundDsohandleKeyword
     case "assert": kind = .poundAssertKeyword
     case "sourceLocation": kind = .poundSourceLocationKeyword
     case "warning": kind = .poundWarningKeyword

Sources/SwiftParser/RawTokenKindSubset.swift

@@ -739,7 +739,6 @@ enum PrimaryExpressionStart: RawTokenKindSubset {
   case period
   case pound
   case poundColorLiteralKeyword
-  case poundDsohandleKeyword
   case poundFileIDKeyword
   case poundFileKeyword
   case poundFileLiteralKeyword
@@ -777,7 +776,6 @@ enum PrimaryExpressionStart: RawTokenKindSubset {
     case .period: self = .period
     case .pound: self = .pound
     case .poundColorLiteralKeyword: self = .poundColorLiteralKeyword
-    case .poundDsohandleKeyword: self = .poundDsohandleKeyword
     case .poundFileIDKeyword: self = .poundFileIDKeyword
     case .poundFileKeyword: self = .poundFileKeyword
     case .poundFileLiteralKeyword: self = .poundFileLiteralKeyword
@@ -818,7 +816,6 @@ enum PrimaryExpressionStart: RawTokenKindSubset {
     case .period: return .period
     case .pound: return .pound
     case .poundColorLiteralKeyword: return .poundColorLiteralKeyword
-    case .poundDsohandleKeyword: return .poundDsohandleKeyword
     case .poundFileIDKeyword: return .poundFileIDKeyword
     case .poundFileKeyword: return .poundFileKeyword
     case .poundFileLiteralKeyword: return .poundFileLiteralKeyword