Remove iconv workaround

Author: o-alquimista

Dockerfile

@@ -17,13 +17,8 @@ RUN apk add --no-cache \
 		file \
 		gettext \
 		git \
-		gnu-libiconv \
 	;
 
-# install gnu-libiconv and set LD_PRELOAD env to make iconv work fully on Alpine image.
-# see https://github.com/docker-library/php/issues/240#issuecomment-763112749
-ENV LD_PRELOAD /usr/lib/preloadable_libiconv.so
-
 ARG APCU_VERSION=5.1.21
 RUN set -eux; \
 	apk add --no-cache --virtual .build-deps \