[S390] Do not clobber personality flags on exec

Analog to git commit 59e4c3a2fe9cb1681bb2cff508ff79466f7585ba
do not clear the additional personality flags on exec. We
need to inherit the personality bits in PER_MASK across exec.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/elf.h

@@ -188,7 +188,8 @@ extern char elf_platform[];
 #define SET_PERSONALITY(ex)					\
 do {								\
 	if (personality(current->personality) != PER_LINUX32)	\
-		set_personality(PER_LINUX);			\
+		set_personality(PER_LINUX |			\
+			(current->personality & ~PER_MASK));	\
 	if ((ex).e_ident[EI_CLASS] == ELFCLASS32)		\
 		set_thread_flag(TIF_31BIT);			\
 	else							\