Contrib: detect zcat vs gzcat

contrib/src/ffmpeg/rules.mak

@@ -112,7 +112,7 @@ FFMPEG_VERSION := git
 ffmpeg: ffmpeg-$(FFMPEG_VERSION).tar.gz .sum-ffmpeg
 	rm -Rf $@ $@-git
 	mkdir -p $@-git
-	zcat "$<" | (cd $@-git && tar xv --strip-components=1)
+	$(ZCAT) "$<" | (cd $@-git && tar xv --strip-components=1)
 ifdef HAVE_WIN32
 	sed -i "s/std=c99/std=gnu99/" $@-$(FFMPEG_VERSION)/configure
 endif

contrib/src/main.mak

@@ -136,6 +136,14 @@ else
 download = $(error Neither curl nor wget found!)
 endif
 
+ifeq ($(shell gzcat --version >/dev/null 2>&1 || echo FAIL),)
+ZCAT = gzcat
+else ifeq ($(shell zcat --version >/dev/null 2>&1 || echo FAIL),)
+ZCAT = zcat
+else
+ZCAT ?= $(error Gunzip client (zcat) not found!)
+endif
+
 ifeq ($(shell sha512sum --version >/dev/null 2>&1 || echo FAIL),)
 SHA512SUM = sha512sum
 else ifeq ($(shell shasum --version >/dev/null 2>&1 || echo FAIL),)

contrib/src/x264/rules.mak

@@ -43,7 +43,7 @@ X264_VERSION := git
 x264: x264-$(X264_VERSION).tar.gz .sum-x264
 	rm -Rf x264-git
 	mkdir -p x264-git
-	zcat "$<" | (cd x264-git && tar xv --strip-components=1)
+	$(ZCAT) "$<" | (cd x264-git && tar xv --strip-components=1)
 	$(MOVE)
 
 .x264: x264