Cherry-pick Fix pkgconfig file parsing on Windows. (#8904) (#8909)

Cherry-pick #8904 to 6.2.

We were not handling Windows line endings properly. It's a pretty simple
one line fix to separate the lines by newlines.

Re-enabling the pkgconfig tests on Windows.

Author: dschaefer2

Sources/PackageLoading/PkgConfig.swift

@@ -273,7 +273,7 @@ internal struct PkgConfigParser {
         variables["pc_sysrootdir"] = sysrootDir ?? Basics.AbsolutePath.root.pathString
 
         let fileContents: String = try fileSystem.readFileContents(pcFile)
-        for line in fileContents.components(separatedBy: "\n") {
+        for line in fileContents.components(separatedBy: .newlines) {
             // Remove commented or any trailing comment from the line.
             let uncommentedLine = removeComment(line: line)
             // Ignore any empty or whitespace line.

Tests/PackageLoadingTests/PkgConfigParserTests.swift

@@ -19,8 +19,6 @@ import struct TSCBasic.ByteString
 
 final class PkgConfigParserTests: XCTestCase {
     func testCircularPCFile() throws {
-        try XCTSkipOnWindows()
-
         let observability = ObservabilitySystem.makeForTesting()
 
         _ = try PkgConfig(
@@ -36,8 +34,6 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testGTK3PCFile() throws {
-        try XCTSkipOnWindows()
-
         try! loadPCFile("gtk+-3.0.pc") { parser in
             XCTAssertEqual(parser.variables, [
                 "libdir": "/usr/local/Cellar/gtk+3/3.18.9/lib",
@@ -58,8 +54,6 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testEmptyCFlags() throws {
-        try XCTSkipOnWindows()
-
         try! loadPCFile("empty_cflags.pc") { parser in
             XCTAssertEqual(parser.variables, [
                 "prefix": "/usr/local/bin",
@@ -74,16 +68,12 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testCFlagsCaseInsensitveKeys() throws {
-        try XCTSkipOnWindows()
-
         try! loadPCFile("case_insensitive.pc") { parser in
             XCTAssertEqual(parser.cFlags, ["-I/usr/local/include"])
         }
     }
 
     func testVariableinDependency() throws {
-        try XCTSkipOnWindows()
-
         try! loadPCFile("deps_variable.pc") { parser in
             XCTAssertEqual(parser.variables, [
                 "prefix": "/usr/local/bin",
@@ -108,8 +98,6 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testEscapedSpaces() throws {
-        try XCTSkipOnWindows()
-
         try! loadPCFile("escaped_spaces.pc") { parser in
             XCTAssertEqual(parser.variables, [
                 "prefix": "/usr/local/bin",
@@ -125,8 +113,6 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testDummyDependency() throws {
-        try XCTSkipOnWindows()
-
         try loadPCFile("dummy_dependency.pc") { parser in
             XCTAssertEqual(parser.variables, [
                 "prefix": "/usr/local/bin",
@@ -213,8 +199,6 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testAbsolutePathDependency() throws {
-        try XCTSkipOnWindows()
-
         let libffiPath = "/usr/local/opt/libffi/lib/pkgconfig/libffi.pc"
 
         try loadPCFile("gobject-2.0.pc") { parser in
@@ -248,8 +232,6 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testUnevenQuotes() throws {
-        try XCTSkipOnWindows()
-
         do {
             try loadPCFile("quotes_failure.pc")
             XCTFail("Unexpected success")
@@ -259,8 +241,6 @@ final class PkgConfigParserTests: XCTestCase {
     }
 
     func testSysrootDir() throws {
-        try XCTSkipOnWindows()
-
         // sysroot should be prepended to all path variables, and should therefore appear in cflags and libs.
         try loadPCFile("gtk+-3.0.pc", sysrootDir: "/opt/sysroot/somewhere") { parser in
             XCTAssertEqual(parser.variables, [

Tests/PackageLoadingTests/PkgConfigTests.swift

@@ -87,8 +87,6 @@ class PkgConfigTests: XCTestCase {
     }
 
     func testEnvVar() throws {
-        try XCTSkipOnWindows()
-
         // Pc file.
         try Environment.makeCustom(["PKG_CONFIG_PATH": inputsDir.pathString]) {
             for result in try pkgConfigArgs(
@@ -152,8 +150,6 @@ class PkgConfigTests: XCTestCase {
     }
 
     func testExplicitPkgConfigDirectories() throws {
-        try XCTSkipOnWindows()
-
         // Pc file.
         for result in try pkgConfigArgs(
             for: SystemLibraryModule(pkgConfig: "Foo"),
@@ -212,8 +208,6 @@ class PkgConfigTests: XCTestCase {
     }
 
     func testDependencies() throws {
-        try XCTSkipOnWindows()
-
         // Use additionalSearchPaths instead of pkgConfigArgs to test handling
         // of search paths when loading dependencies.
         let result = try PkgConfig(