Fix multido compilation on ARM

The previous multi-build implementation was copying the config.status from the parent
multilib directory when building the different semihosting variants. It did so because
the configuration doesn't change. However when you use a relative path to configure it
turns out that the paths inside the config.status are also relative.

To fix this, the srcdir is adjusted from the initial configuration instead of copying it.

Tested on aarch64-none-elf and arm-none-eabi.

Signed-off-by: Tamar Christina <tamar.christina@arm.com>

libgloss/multi-build.in

@@ -17,9 +17,9 @@ multi-do:
 	      destpre=`echo $${rootpre}/$${dir}`/; export destpre; \
 	      if ! test -d $${destpre} ; then \
 		mkdir -p $${destpre}; \
-		cp config.status $${destpre}; \
 		cd $${destpre}; \
-		$(SHELL) config.status; \
+		config_cmd=`../config.status --config | sed -re "s:--srcdir=([^/]):--srcdir=../\1:"`; \
+		$(SHELL) -c "$(SHELL) $${srcrootpre}/configure $${config_cmd}";\
 		sed -e "s:^MULTIDIRS[[:space:]]*+=.*$$:MULTIDIRS = :" \
 		    -e "s:^MULTILIBNAME[[:space:]]*=.*$$:MULTILIBNAME = MULTIDIR_$${dir}_NAME:" \
 		    -e "s:^MULTI_FLAGS_FOR_TARGET[[:space:]]*=.*$$:MULTI_FLAGS_FOR_TARGET = MULTIDIR_$${dir}_FLAGS:" \