Make --ld-path option consistently use single dash (#1441)

The vast majority of other options on Swift Driver already use a single dash.

Author: MaxDesiatov

Sources/SwiftOptions/Options.swift

@@ -531,7 +531,7 @@ extension Option {
   public static let json_: Option = Option("--json", .flag, alias: Option.json, attributes: [.noDriver], helpText: "Print output in JSON format.")
   public static let j: Option = Option("-j", .joinedOrSeparate, attributes: [.doesNotAffectIncrementalBuild], metaVar: "<n>", helpText: "Number of commands to execute in parallel")
   public static let LEQ: Option = Option("-L=", .joined, alias: Option.L, attributes: [.frontend, .doesNotAffectIncrementalBuild, .argumentIsPath], group: .linkerOption)
-  public static let ldPath: Option = Option("--ld-path=", .joined, attributes: [.helpHidden, .doesNotAffectIncrementalBuild, .argumentIsPath], helpText: "Specifies the path to the linker to be used")
+  public static let ldPath: Option = Option("-ld-path=", .joined, attributes: [.helpHidden, .doesNotAffectIncrementalBuild, .argumentIsPath], helpText: "Specifies the path to the linker to be used")
   public static let libc: Option = Option("-libc", .separate, attributes: [], helpText: "libc runtime library to use")
   public static let libraryLevelEQ: Option = Option("-library-level=", .joined, alias: Option.libraryLevel, attributes: [.helpHidden, .frontend, .moduleInterface], metaVar: "<level>")
   public static let libraryLevel: Option = Option("-library-level", .separate, attributes: [.helpHidden, .frontend, .moduleInterface], metaVar: "<level>", helpText: "Library distribution level 'api', 'spi' or 'other' (the default)")

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -1679,7 +1679,7 @@ final class SwiftDriverTests: XCTestCase {
 
     do {
       // macOS target
-      var driver = try Driver(args: commonArgs + ["-emit-library", "-target", "x86_64-apple-macosx10.15", "-Onone", "-use-ld=foo", "--ld-path=/bar/baz"], env: env)
+      var driver = try Driver(args: commonArgs + ["-emit-library", "-target", "x86_64-apple-macosx10.15", "-Onone", "-use-ld=foo", "-ld-path=/bar/baz"], env: env)
       let plannedJobs = try driver.planBuild()
 
       XCTAssertEqual(3, plannedJobs.count)
@@ -1691,7 +1691,7 @@ final class SwiftDriverTests: XCTestCase {
       let cmd = linkJob.commandLine
       XCTAssertTrue(cmd.contains(.flag("-dynamiclib")))
       XCTAssertTrue(cmd.contains(.flag("-fuse-ld=foo")))
-      XCTAssertTrue(cmd.contains(.joinedOptionAndPath("--ld-path=", try VirtualPath(path: "/bar/baz"))))
+      XCTAssertTrue(cmd.contains(.joinedOptionAndPath("-ld-path=", try VirtualPath(path: "/bar/baz"))))
       XCTAssertTrue(cmd.contains(.flag("--target=x86_64-apple-macosx10.15")))
       XCTAssertEqual(linkJob.outputs[0].file, try VirtualPath(path: "libTest.dylib"))