Build fixes for fnl/musl

services/native_support/make_pty_pair.cc

Index: services/native_support/make_pty_pair.cc
diff --git a/services/native_support/make_pty_pair.cc b/services/native_support/make_pty_pair.cc
index 2af21f5216e7f79526a47e2f2b5d61fca1a5e36b..0a4450f33ab4a008dd95dc8fcc7b8e70c7cc3fc0 100644
--- a/services/native_support/make_pty_pair.cc
+++ b/services/native_support/make_pty_pair.cc
@@ -23,11 +23,15 @@ bool MakePtyPair(base::ScopedFD* master_fd,
   DCHECK(!slave_fd->is_valid());  // Not very wrong, but unlikely.
   DCHECK(errno_value);
 
-  // TODO(vtl): |getpt()| is a glibc extension.
+#if defined(FNL_MUSL)
+  base::ScopedFD master(posix_openpt(O_RDWR | O_NOCTTY));
+#else
+  // Android doesn't yet have posix_openpt
   base::ScopedFD master(getpt());
+#endif
   if (!master.is_valid()) {
     *errno_value = errno;
-    PLOG(ERROR) << "getpt()";
+    PLOG(ERROR) << "posix_openpt/getpt";
     return false;
   }