pam: does not need flex

package/pam/Makefile

@@ -9,7 +9,7 @@ PKG_RELEASE:=		1
 PKG_HASH:=		1dad9cb50b4a19accd7d7b9716777caf5a0f33d26f018f27d63e9e095998f12b
 PKG_DESCR:=		pluggable authentication modules
 PKG_DEPENDS_GLIBC:=	libxcrypt
-PKG_BUILDDEP:=		flex meson-host
+PKG_BUILDDEP:=		meson-host
 PKG_BUILDDEP_GLIBC:=	libxcrypt
 PKG_SECTION:=		sys/misc
 PKG_URL:=		http://www.linux-pam.org/