Implement <pty.h>.

Based on the package/apps/Terminal implementation. I'll switch them over
shortly. This also lets us build the toybox version of netcat.

Change-Id: Ia922a100141a67409264b43b937eeca07b21f344
diff --git a/tests/Android.mk b/tests/Android.mk
index 93ab9bd..3f5a112 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -72,6 +72,7 @@
     mntent_test.cpp \
     netdb_test.cpp \
     pthread_test.cpp \
+    pty_test.cpp \
     regex_test.cpp \
     sched_test.cpp \
     search_test.cpp \
@@ -108,6 +109,7 @@
     uchar_test.cpp \
     uniqueptr_test.cpp \
     unistd_test.cpp \
+    utmp_test.cpp \
     wchar_test.cpp \
 
 libBionicStandardTests_cflags := \
@@ -309,7 +311,7 @@
     libBionicStandardTests \
 
 bionic-unit-tests-glibc_ldlibs := \
-    -lrt -ldl \
+    -lrt -ldl -lutil \
 
 bionic-unit-tests-glibc_c_includes := \
     bionic/libc \