dovecot: remove incorrect PKG_BUILD_DEPENDS

The package Makefile contains a PKG_BUILD_DEPENDS=libiconv
line, which apart from being incorrect if libiconv-full is
specified in the build configuration, is also unnecessary,
since the package Makefile already includes nls.mk which
sets PKG_BUILD_DEPENDS appropriately.

Signed-off-by: Ian Cooper <iancooper@hotmail.com>

mail/dovecot/Makefile

@@ -20,7 +20,6 @@ PKG_LICENSE:=LGPL-2.1-only MIT BSD-3-Clause
 PKG_LICENSE_FILES:=COPYING COPYING.LGPL COPYING.MIT
 PKG_CPE_ID:=cpe:/a:dovecot:dovecot
 
-PKG_BUILD_DEPENDS:=libiconv
 PKG_CONFIG_DEPENDS:= \
 	CONFIG_DOVECOT_GSSAPI \
 	CONFIG_DOVECOT_LDAP \