Clean up fpathconf(3)/pathconf(3).

fpathconf(3) and pathconf(3) can share code. There's no such
header file as <pathconf.h>. glibc/POSIX and BSD disagree about where
the _POSIX_* definitions should go.

Change-Id: I4a67f1595c9f5fbb26700a131178eedebd6bf712
diff --git a/libc/Android.mk b/libc/Android.mk
index a8778c5..cb55fd4 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -49,7 +49,6 @@
     bionic/ioctl.c \
     bionic/isatty.c \
     bionic/memmem.c \
-    bionic/pathconf.c \
     bionic/pututline.c \
     bionic/sched_cpualloc.c \
     bionic/sched_cpucount.c \
@@ -142,6 +141,7 @@
     bionic/mntent.cpp \
     bionic/NetdClientDispatch.cpp \
     bionic/open.cpp \
+    bionic/pathconf.cpp \
     bionic/pause.cpp \
     bionic/pipe.cpp \
     bionic/poll.cpp \