Allow opening a named pipe on MacOS and Linux.

runtime/bin/file_linux.cc

Index: runtime/bin/file_linux.cc
diff --git a/runtime/bin/file_linux.cc b/runtime/bin/file_linux.cc
index 309971531c94050179c43745ca745f0f6d541a4b..0cd9dec4469633f1a0d8ffda3524e3b633258b27 100644
--- a/runtime/bin/file_linux.cc
+++ b/runtime/bin/file_linux.cc
@@ -155,8 +155,8 @@ File* File::ScopedOpen(const char* name, FileOpenMode mode) {
   // Report errors for non-regular files.
   struct stat64 st;
   if (TEMP_FAILURE_RETRY(stat64(name, &st)) == 0) {
-    // Only accept regular files and character devices.
-    if (!S_ISREG(st.st_mode) && !S_ISCHR(st.st_mode)) {
+    // Only accept regular files, character devices, and pipes.
+    if (!S_ISREG(st.st_mode) && !S_ISCHR(st.st_mode) && !S_ISFIFO(st.st_mode)) {
       errno = (S_ISDIR(st.st_mode)) ? EISDIR : ENOENT;
       return NULL;
     }