fdtrack: add wrappers for pipe, pipe2.

Bug: https://issuetracker.google.com/154450436
Test: bionic-unit-tests
Change-Id: I66826f312a65ab9f1bd8193bf684e330baa952dc
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index ab309e6..cf7d58b 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -126,7 +126,7 @@
 int         __fcntl:fcntl(int, int, void*)  lp64
 int         flock(int, int)   all
 int         __fchmod:fchmod(int, mode_t)  all
-int         pipe2(int*, int) all
+int         __pipe2:pipe2(int*, int) all
 int         __dup:dup(int)  all
 int         __dup3:dup3(int, int, int)   all
 int         fsync(int)  all