Add dummy implementation of _UI_longjmp_cont().

(Logical change 1.268)
diff --git a/src/x86/siglongjmp.S b/src/x86/siglongjmp.S
index 0057027..c43c984 100644
--- a/src/x86/siglongjmp.S
+++ b/src/x86/siglongjmp.S
@@ -2,7 +2,9 @@
 	   can't work on x86 until we take advantage of DWARF2 unwind info.  */
 
 	.globl _UI_siglongjmp_cont
+	.globl _UI_longjmp_cont
 
 _UI_siglongjmp_cont:
+_UI_longjmp_cont:
 #warning fix me
 	ret
diff --git a/src/x86_64/siglongjmp.S b/src/x86_64/siglongjmp.S
index 0057027..c43c984 100644
--- a/src/x86_64/siglongjmp.S
+++ b/src/x86_64/siglongjmp.S
@@ -2,7 +2,9 @@
 	   can't work on x86 until we take advantage of DWARF2 unwind info.  */
 
 	.globl _UI_siglongjmp_cont
+	.globl _UI_longjmp_cont
 
 _UI_siglongjmp_cont:
+_UI_longjmp_cont:
 #warning fix me
 	ret