Deb: Build depend on libcurl4-openssl-dev as primary option

The package libcurl4-dev is a virtual package, and no package with that
name actually exists. Depend on libcurl4-openssl-dev as the primary
option in case no libcurl4-dev providing package has been installed, and
if some of them (libcurl4-gnutls-dev, libcurl4-nss-dev,
libcurl4-openssl-dev ) are installed, they also satisfy the dependency
via the virtual package.

The Travis-CI still runs on libcurl3-dev as Travis-CI also runs Ubuntu
Xenial which does not yet have libcurl4 available.

This complements commit 2e0a40bdf0.

debian/autobake-deb.sh

@@ -88,7 +88,7 @@ sed -i -e "/Package: mariadb-plugin-tokudb/,/^$/d" debian/control
 # attempt to build using older libpcre3-dev (SIC!)
 if ! apt-cache madison libpcre2-dev | grep --quiet 'libpcre2-dev'
 then
-  sed 's/libpcre2-dev/libpcre3-dev/' -i debian/control
+  sed 's/libcurl4-openssl-dev | libcurl4-dev/libpcre3-dev/' -i debian/control
 fi
 
 # Cassandra, Mroonga etc never built on Travis CI anyway, see build flags above

debian/control

@@ -13,7 +13,7 @@ Build-Depends: bison,
                libaio-dev [linux-any],
                libboost-dev,
                libcrack2-dev (>= 2.9.0),
-               libcurl4-dev,
+               libcurl4-openssl-dev | libcurl4-dev,
                libjemalloc-dev (>= 3.0.0~) [linux-any],
                libjudy-dev,
                libkrb5-dev,