package/Makefile.in: fix musl handling

Until now, we had no support for full NLS with the musl C library:
BR2_NEEDS_GETTEXT was only true for uClibc. But the musl C library
provides a stub gettext implementation, which some packages were
failing to recognize as being usable, and therefore we are passing
autoconf cache variables to hint those packages that yes, the C
library has a usable gettext implementation.

However, we are going to enable full NLS support for musl, by giving
the possibility to build gettext libintl with musl. In such a case, we
do not want packages to use the gettext implementation of the C
library, but really the one provided by gettext libintl.

Therefore, we should only pre-seed the
gt_cv_func_gnugettext1_libc*=yes variables if we're on musl but
without gettext libintl. Otherwise packages will fail building because:

 - libintl.h is the one from the full-blown gettext implementation, so
   it assumes the package will link against -lintl

 - the package thinks gettext is provided by the C library, so it
   doesn't link with -lintl

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/Makefile.in

@@ -338,7 +338,12 @@ endif
 # AM_GNU_GETTEXT misdetects musl gettext support.
 # musl currently implements api level 1 and 2 (basic + ngettext)
 # http://www.openwall.com/lists/musl/2015/04/16/3
-ifeq ($(BR2_TOOLCHAIN_USES_MUSL),y)
+#
+# These autoconf variables should only be pre-seeded when the minimal
+# gettext implementation of musl is used. When the full blown
+# implementation provided by gettext libintl is used, auto-detection
+# works fine, and pre-seeding those values is actually wrong.
+ifeq ($(BR2_TOOLCHAIN_USES_MUSL):$(BR2_PACKAGE_GETTEXT_PROVIDES_LIBINTL),y:)
 BR2_GT_CV_FUNC_GNUGETTEXT_LIBC = \
 	gt_cv_func_gnugettext1_libc=yes \
 	gt_cv_func_gnugettext2_libc=yes