https://bugs.gentoo.org/721914

--- a/Makefile.in
+++ b/Makefile.in
@@ -124,7 +124,7 @@ CONFIG_HEADER = config.h
 CONFIG_CLEAN_FILES =
 CONFIG_CLEAN_VPATH_FILES =
 LIBRARIES = $(noinst_LIBRARIES)
-AR = ar
+AR := ar
 ARFLAGS = cru
 AM_V_AR = $(am__v_AR_@AM_V@)
 am__v_AR_ = $(am__v_AR_@AM_DEFAULT_V@)