bfin: switch to generic vfork, get rid of pointless wrappers

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/blackfin/include/asm/unistd.h b/arch/blackfin/include/asm/unistd.h
index b4ec1bb..460514a1 100644
--- a/arch/blackfin/include/asm/unistd.h
+++ b/arch/blackfin/include/asm/unistd.h
@@ -447,6 +447,7 @@
 #define __ARCH_WANT_SYS_RT_SIGACTION
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_EXECVE
+#define __ARCH_WANT_SYS_VFORK
 
 /*
  * "Conditional" syscalls