package/gzip: add host variant

In case someone is building on a musl-based distro (Alpine), we do as
for the target variant, and force the fflush_stdin detection.

We however do not do the /bin/sh trick, because we are building
natively, so the shell check is working.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/gzip/gzip.mk

@@ -12,6 +12,7 @@ GZIP_CONF_OPTS = --exec-prefix=/
 GZIP_LICENSE = GPL-3.0+
 GZIP_LICENSE_FILES = COPYING
 GZIP_CONF_ENV += gl_cv_func_fflush_stdin=yes
+HOST_GZIP_CONF_ENV += gl_cv_func_fflush_stdin=yes
 # configure substitutes $(SHELL) for the shell shebang in scripts like
 # gzexe. Unfortunately, the same $(SHELL) variable will also be used by
 # make to run its commands. Fortunately, /bin/sh is always a POSIX shell
@@ -21,3 +22,4 @@ GZIP_CONF_ENV += gl_cv_func_fflush_stdin=yes
 GZIP_CONF_ENV += ac_cv_path_shell=/bin/sh
 
 $(eval $(autotools-package))
+$(eval $(host-autotools-package))