libc: update alarm() implementation to return 0 on error.

This matches the GLibc behaviour, and allows alarm(0xFFFFFFFF) to return 0.

Change-Id: I419aa71b27d6bb2015d15ba6b6112bf62eadcbb8
diff --git a/libc/docs/CHANGES.TXT b/libc/docs/CHANGES.TXT
index cbca6cb..96f25d3 100644
--- a/libc/docs/CHANGES.TXT
+++ b/libc/docs/CHANGES.TXT
@@ -27,6 +27,10 @@
 - <unistd.h>: add missing declaration for truncate(). The implementation
   was already here since Android 1.5.
 
+  modify implementation of alarm() to return 0 in case of error (i.e.
+  if a value larger than 0x7fffffff seconds is passed to it). This
+  makes the implementation compliant with the GLibc behaviour.
+
 - <wchar.h>: small fixes to really support wchar_t in Bionic (not there yet).
 
      the size of wchar_t is still 32-bit (decided by the compiler)
@@ -66,6 +70,7 @@
 - <sys/vfs.h>: fixed implementation of fstatfs() (also fixes fpathconf()
   which uses it).
 
+
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 Differences between Android 2.2. and Android 2.1: