[linux] define _GNU_SOURCE for process_vm_readv

Author: andrurogerz

tools/swift-inspect/Package.swift

@@ -27,7 +27,8 @@ let package = Package(
             name: "SwiftInspectLinux",
             dependencies: ["LinuxSystemHeaders"],
             path: "Sources/SwiftInspectLinux",
-            exclude: ["SystemHeaders"]),
+            exclude: ["SystemHeaders"],
+            cSettings: [.define("_GNU_SOURCE", to: "1")]),
         .systemLibrary(
             name: "LinuxSystemHeaders",
             path: "Sources/SwiftInspectLinux/SystemHeaders"),

tools/swift-inspect/Sources/SwiftInspectLinux/SystemHeaders/uio.h

@@ -11,10 +11,3 @@
 //===----------------------------------------------------------------------===//
 
 #include <sys/uio.h>
-
-// process_vm_readv/writeva are available in glibc but are not in the headers
-// provided with the Swift toolchain
-ssize_t process_vm_readv(pid_t, const struct iovec*, unsigned long,
-    const struct iovec*, unsigned long, unsigned long);
-ssize_t process_vm_writev(pid_t, const struct iovec*, unsigned long,
-    const struct iovec*, unsigned long, unsigned long);