Update imagick package to 3.7.0

Also apply hack patch for preprocessor build failures

Author: tianon

Dockerfile.template

@@ -85,9 +85,25 @@ RUN set -ex; \
 # WARNING: imagick is likely not supported on Alpine: https://github.com/Imagick/imagick/issues/328
 {{ ) else "" end -}}
 # https://pecl.php.net/package/imagick
-	pecl install imagick-3.6.0; \
+{{ if true then ( -}}
+# https://github.com/Imagick/imagick/commit/5ae2ecf20a1157073bad0170106ad0cf74e01cb6 (causes a lot of build failures, but strangely only intermittent ones 🤔)
+# see also https://github.com/Imagick/imagick/pull/641
+# this is "pecl install imagick-3.7.0", but by hand so we can apply a small hack / part of the above commit
+	curl -fL -o imagick.tgz 'https://pecl.php.net/get/imagick-3.7.0.tgz'; \
+	echo '5a364354109029d224bcbb2e82e15b248be9b641227f45e63425c06531792d3e *imagick.tgz' | sha256sum -c -; \
+	tar --extract --directory /tmp --file imagick.tgz imagick-3.7.0; \
+	grep '^//#endif$' /tmp/imagick-3.7.0/Imagick.stub.php; \
+	test "$(grep -c '^//#endif$' /tmp/imagick-3.7.0/Imagick.stub.php)" = '1'; \
+	sed -i -e 's!^//#endif$!#endif!' /tmp/imagick-3.7.0/Imagick.stub.php; \
+	grep '^//#endif$' /tmp/imagick-3.7.0/Imagick.stub.php && exit 1 || :; \
+	docker-php-ext-install /tmp/imagick-3.7.0; \
+	rm -rf imagick.tgz /tmp/imagick-3.7.0; \
+{{ # TODO when imagick has another release, we should ditch this whole block and just update instead -}}
+{{ ) else ( -}}
+	pecl install imagick-3.7.0; \
 	docker-php-ext-enable imagick; \
 	rm -r /tmp/pear; \
+{{ ) end -}}
 	\
 # some misbehaving extensions end up outputting to stdout 🙈 (https://github.com/docker-library/wordpress/issues/669#issuecomment-993945967)
 	out="$(php -r 'exit(0);')"; \