Merge pull request #24108 from colemancda/posixErrorGlibc-5.1

[5.1] Cherry-pick: [stdlib] Include POSIXError as part of Glibc

Author: shahmishal

stdlib/public/Platform/CMakeLists.txt

@@ -20,6 +20,7 @@ add_swift_target_library(swiftDarwin ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_
 add_swift_target_library(swiftGlibc ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVERLAY
     Glibc.swift.gyb
     ${swift_platform_sources}
+    POSIXError.swift
 
     SWIFT_COMPILE_FLAGS "${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS}"
     LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"