contrib: remove use of gas-preprocessor.pl on iOS armv7

According to #24678 it should work with Clang 5 and above. Not sure there are
iOS/XCode toolchain still available that can target iOS 9 with an older Clang.

The iOS armv7 target continues to build assembler as before.

contrib/src/ffmpeg/rules.mak

@@ -138,9 +138,6 @@ FFMPEGCONF += --cpu=core2
 endif
 ifdef HAVE_IOS
 FFMPEGCONF += --enable-pic --extra-ldflags="$(EXTRA_CFLAGS) -isysroot $(IOS_SDK)"
-ifeq ($(ARCH),arm) # gas-preprocessor.pl
-FFMPEGCONF += --as="$(AS)"
-endif
 endif
 endif
 

contrib/src/main.mak

@@ -120,13 +120,6 @@ endif
 
 CCAS=$(CC) -c
 
-ifdef HAVE_IOS
-ifeq ($(ARCH),arm)
-AS=perl $(abspath $(VLC_TOOLS)/bin/gas-preprocessor.pl) $(CC)
-CCAS=gas-preprocessor.pl $(CC) -c
-endif
-endif
-
 LN_S = ln -s
 ifdef HAVE_WIN32
 MINGW_W64_VERSION := $(shell echo "__MINGW64_VERSION_MAJOR" | $(CC) $(CFLAGS) -E -include _mingw.h - | tail -n 1)