Set directory-wide libtool tag correctly

modules/arm_neon/Modules.am

-# When using a specific AS tool instead of gcc libtool goes mad
-# without this. (This is the case with iOS).
-LIBTOOL=@LIBTOOL@ --tag=CC
+AM_LIBTOOLFLAGS=--tag=CC
 
 libaudio_format_neon_plugin_la_SOURCES = \
 	s32_s16.S \

modules/gui/macosx/Modules.am

-# Automake forgets to add a proper tag to libtool with Objective-C files.
-# Moreovcer Libtool should default tag to CC when none is specified but
-# obviously does not. Here is a fix for that.
-LIBTOOL=@LIBTOOL@ --tag=CC
+AM_LIBTOOLFLAGS=--tag=CC
 
 SOURCES_macosx = \
 	CompatibilityFixes.h \

modules/gui/macosx_dialog_provider/Modules.am

-# Automake forgets to add a proper tag to libtool with Objective-C files.
-# Moreocer Libtool should default tag to CC when none is specified but
-# obviously does not. Here is a fix for that.
-LIBTOOL=@LIBTOOL@ --tag=CC
+AM_LIBTOOLFLAGS=--tag=CC
 
 SOURCES_macosx_dialog_provider = \
     VLCLoginPanel.m \

modules/gui/minimal_macosx/Modules.am

-# Automake forgets to add a proper tag to libtool with Objective-C files.
-# Moreocer Libtool should default tag to CC when none is specified but
-# obviously does not. Here is a fix for that.
-LIBTOOL=@LIBTOOL@ --tag=CC
+AM_LIBTOOLFLAGS=--tag=CC
 
 SOURCES_minimal_macosx = \
 	intf.m \

modules/notify/Modules.am

-# Automake forgets to add a proper tag to libtool with Objective-C files.
-# Moreocer Libtool should default tag to CC when none is specified but
-# obviously does not. Here is a fix for that.
-LIBTOOL=@LIBTOOL@ --tag=CC
+AM_LIBTOOLFLAGS=--tag=CC
 
 SOURCES_growl = growl.m
 SOURCES_notify = notify.c

modules/video_output/Modules.am

-# Automake forgets to add a proper tag to libtool with Objective-C files.
-# Moreocer Libtool should default tag to CC when none is specified but
-# obviously does not. Here is a fix for that.
-LIBTOOL=@LIBTOOL@ --tag=CC
+AM_LIBTOOLFLAGS=--tag=CC
 
 SOURCES_aa = aa.c
 SOURCES_fb = fb.c