Revert "curl: update to 7.52.0."

This reverts commit 35b3865b8d.

Attention! We will release a patch update within a few days to fix a
serious security problem found in curl 7.52.0. You may consider
holding off until then.

https://curl.haxx.se/download.html

Thanks @ebfe

srcpkgs/curl/template

@@ -1,7 +1,7 @@
 # Template build file for 'curl'.
 pkgname=curl
-version=7.52.0
-revision=1
+version=7.51.0
+revision=2
 build_style=gnu-configure
 configure_args="ac_cv_sizeof_off_t=8 --without-gssapi
  --enable-threaded-resolver --enable-ipv6 $(vopt_with rtmp)
@@ -19,7 +19,7 @@ maintainer="Juan RP <xtraeme@voidlinux.eu>"
 license="MIT"
 homepage="http://curl.haxx.se"
 distfiles="$homepage/download/$pkgname-$version.tar.bz2"
-checksum=b9a2e18b4785eb75ad84598720e1559e1c53550ea011c0e00becdb94e2df5cc6
+checksum=7f8240048907e5030f67be0a6129bc4b333783b9cca1391026d700835a788dde
 
 build_options="gnutls ldap rtmp ssh ssl"
 build_options_default="ssh ssl"