fix Issue 18649 - curl on Ubuntu 18.04 depends on libcurl4, ...

... .deb installer depends on libcurl3

- depend on libcurl4 | libcurl3 alternative
- degrading libcurl from dependency to recommends would be welcome,
  but does not work because recommendations are not installed for raw
  .deb packages (--fix-broken only installs dependencies).
  `dpkg -i dmd_2.079.1-0_amd64.deb && apt-get --fix-broken install`
- also add suggested libcurl-dev alternative

linux/dmd_deb.sh

@@ -344,8 +344,8 @@ else
 
 
 	# set deb package dependencies
-	DEPENDS="libc6, libc6-dev, gcc, libgcc1, libstdc++6, libcurl3"
-	SUGGESTS="libcurl4-openssl-dev, gcc-multilib"
+	DEPENDS='libc6, libc6-dev, gcc, libgcc1, libstdc++6, libcurl4 | libcurl3'
+	SUGGESTS='gcc-multilib, libcurl4-openssl-dev | libcurl4-gnutls-dev | libcurl4-nss-dev'
 
 
 	# create control file

linux/dmd_phobos.sh

@@ -203,7 +203,7 @@ else
 
 
 	# set deb package dependencies
-	DEPENDS="libc6, libcurl3"
+	DEPENDS="libc6, libcurl4 | libcurl3"
 
 
 	# create control file