Add Musl import support for static linking

Sources/Path+FileManager.swift

@@ -1,6 +1,8 @@
 import Foundation
-#if os(Linux)
+#if canImport(Glibc)
 import Glibc
+#elseif canImport(Musl)
+import Musl
 #endif
 
 public extension Pathish {

Sources/Path.swift

@@ -1,10 +1,13 @@
 import Foundation
-#if !os(Linux)
+#if canImport(Darwin)
 import func Darwin.realpath
 let _realpath = Darwin.realpath
-#else
+#elseif canImport(Glibc)
 import func Glibc.realpath
 let _realpath = Glibc.realpath
+#elseif canImport(Musl)
+import func Musl.realpath
+let _realpath = Musl.realpath
 #endif
 
 public typealias PathStruct = Path

Sources/PathToBool.swift

@@ -1,8 +1,10 @@
 import Foundation
-#if os(Linux)
-import func Glibc.access
-#else
+#if canImport(Darwin)
 import Darwin
+#elseif canImport(Glibc)
+import func Glibc.access
+#elseif canImport(Musl)
+import func Musl.access
 #endif
 
 public extension Pathish {