Merge pull request #49 from simonjbeaumont/sb/musl-support

Support compiling against Musl

Author: guoye-zhang

Sources/HTTPTypes/HTTPFields.swift

@@ -16,6 +16,8 @@
 import os.lock
 #elseif canImport(Glibc)
 import Glibc
+#elseif canImport(Musl)
+import Musl
 #elseif canImport(WASILibc)
 import WASILibc
 #endif