Put bsd_signal back.

With this change (and all the others below it in the stack), the only
difference between the arm android-9 libc.so in r13-beta1 and the one
we are now generating is the addition of LIBC_N and LIBC_O versions.

Test: make ndk, readelf stub libc.so to check symbol exists
Bug: https://github.com/android-ndk/ndk/issues/160
Change-Id: Iedab32592b2d979f3cc922ffd4ed406427de3dda
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index 8458640..8c3da20 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -1291,38 +1291,39 @@
     tmpfile64; # introduced=24
 } LIBC;
 
-LIBC_O { # future
+LIBC_O {
   global:
-    catclose;
-    catgets;
-    catopen;
-    ctermid;
-    endgrent;
-    endpwent;
-    futimes;
-    futimesat;
-    getdomainname;
-    getgrent;
-    getpwent;
-    getsubopt;
-    hasmntopt;
-    lutimes;
-    mblen;
-    pthread_getname_np;
-    quotactl;
-    setdomainname;
-    setgrent;
-    setpwent;
-    sighold;
-    sigignore;
-    sigpause;
-    sigrelse;
-    sigset;
-    sync_file_range;
-    towctrans;
-    towctrans_l;
-    wctrans;
-    wctrans_l;
+    bsd_signal; # arm x86 mips nobrillo versioned=26
+    catclose; # future
+    catgets; # future
+    catopen; # future
+    ctermid; # future
+    endgrent; # future
+    endpwent; # future
+    futimes; # future
+    futimesat; # future
+    getdomainname; # future
+    getgrent; # future
+    getpwent; # future
+    getsubopt; # future
+    hasmntopt; # future
+    lutimes; # future
+    mblen; # future
+    pthread_getname_np; # future
+    quotactl; # future
+    setdomainname; # future
+    setgrent; # future
+    setpwent; # future
+    sighold; # future
+    sigignore; # future
+    sigpause; # future
+    sigrelse; # future
+    sigset; # future
+    sync_file_range; # future
+    towctrans; # future
+    towctrans_l; # future
+    wctrans; # future
+    wctrans_l; # future
 } LIBC_N;
 
 LIBC_PRIVATE {
@@ -1511,7 +1512,6 @@
     atexit; # arm
     bcopy; # arm x86 mips nobrillo
     bzero; # arm x86 mips nobrillo
-    bsd_signal; # arm x86 mips nobrillo
     dlmalloc; # arm x86 mips nobrillo
     dlmalloc_inspect_all; # arm x86 mips nobrillo
     dlmalloc_trim; # arm x86 mips nobrillo