Ignore all __weak_alias in OpenBSD libC.

GCC assembler allows xyz to be redeclared as weak,
by __weak_alias(xyz, _xyz), while _xyz is undefined.
Clang does not like that but silently generates no code.
It will reject its own .s file if the assembly code is saved first.
Since we have no reason to define xyz or _xyz as weak symbol now,
and _xyz is a macro to xyz, we simplify libC to have only
xyz defined as global.

BUG: 17186746
Change-Id: I24b154425838683cae69248cc750c59e26fd5467
diff --git a/libc/include/sys/cdefs_elf.h b/libc/include/sys/cdefs_elf.h
index 6bb0a57..a40a867 100644
--- a/libc/include/sys/cdefs_elf.h
+++ b/libc/include/sys/cdefs_elf.h
@@ -34,10 +34,6 @@
     __asm__(".global " #alias "\n" \
             #alias " = " #sym);
 
-#define __weak_alias(alias,sym) \
-    __asm__(".weak " #alias "\n" \
-            #alias " = " #sym);
-
 /* We use __warnattr instead of __warn_references.
  * TODO: remove this and put an empty definition in one of the upstream-* compatibility headers.
  */
diff --git a/libc/upstream-netbsd/android/include/namespace.h b/libc/upstream-netbsd/android/include/namespace.h
index 5df543c..630ea9b 100644
--- a/libc/upstream-netbsd/android/include/namespace.h
+++ b/libc/upstream-netbsd/android/include/namespace.h
@@ -17,11 +17,6 @@
 #ifndef _BIONIC_NETBSD_NAMESPACE_H_included
 #define _BIONIC_NETBSD_NAMESPACE_H_included
 
-// NetBSD uses __weak_alias on a lot of functions. We don't want that.
-#if defined(__weak_alias)
-#undef __weak_alias
-#endif
-
 __LIBC_HIDDEN__ int __res_enable_mt(void);
 __LIBC_HIDDEN__ int __res_disable_mt(void);
 
diff --git a/libc/upstream-openbsd/android/include/openbsd-compat.h b/libc/upstream-openbsd/android/include/openbsd-compat.h
index b9768e1..630094d 100644
--- a/libc/upstream-openbsd/android/include/openbsd-compat.h
+++ b/libc/upstream-openbsd/android/include/openbsd-compat.h
@@ -32,6 +32,9 @@
 #define _warn warn
 #define _warnx warnx
 
+/* Ignore all __weak_alias in OpenBSD. */
+#define __weak_alias(alias,sym)
+
 /* OpenBSD's <ctype.h> uses these names, which conflicted with stlport.
  * Additionally, we changed the numeric/digit type from N to D for libcxx.
  */