sleep/usleep: switch to trivial implementations.

Upstream keeps rearranging the deckchairs for these, so let's just
switch to the [roughly] one-liners rather than track that...

Test: treehugger
Change-Id: If655cf7a7f316657de44d41fadd43a8c55ee6f23
diff --git a/libc/Android.bp b/libc/Android.bp
index 3e2ee1d..8eefe10 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -271,8 +271,6 @@
     defaults: ["libc_defaults"],
     srcs: [
         "upstream-freebsd/lib/libc/gen/ldexp.c",
-        "upstream-freebsd/lib/libc/gen/sleep.c",
-        "upstream-freebsd/lib/libc/gen/usleep.c",
         "upstream-freebsd/lib/libc/stdlib/getopt_long.c",
         "upstream-freebsd/lib/libc/stdlib/hcreate.c",
         "upstream-freebsd/lib/libc/stdlib/hcreate_r.c",
@@ -1178,6 +1176,7 @@
         "bionic/sigaction.cpp",
         "bionic/signal.cpp",
         "bionic/sigprocmask.cpp",
+        "bionic/sleep.cpp",
         "bionic/spawn.cpp",
         "bionic/stat.cpp",
         "bionic/stdlib_l.cpp",
@@ -1212,6 +1211,7 @@
         "bionic/tmpfile.cpp",
         "bionic/umount.cpp",
         "bionic/unlink.cpp",
+        "bionic/usleep.cpp",
         "bionic/wait.cpp",
         "bionic/wchar.cpp",
         "bionic/wchar_l.cpp",