Add strtof_l and strtod_l.

libc++ needs these now. Add shims to match the others.

Test: make checkbuild tests
Bug: http://b/31639993
Change-Id: Ifec6c32099145d8d3d1a5639a4809e5e9f553c33
diff --git a/libc/libc.arm64.map b/libc/libc.arm64.map
index 2393d22..28755d4 100644
--- a/libc/libc.arm64.map
+++ b/libc/libc.arm64.map
@@ -1228,6 +1228,10 @@
     sigpause; # future
     sigrelse; # future
     sigset; # future
+    strtod_l; # future
+    strtof_l; # future
+    strtol_l; # future
+    strtoul_l; # future
     sync_file_range; # future
     towctrans; # future
     towctrans_l; # future