Revert "Removed commands for building libcurl from makefile.unix. It should be installed seperately."

This reverts commit e07d05b1c9bbef4ac5ec0bc0c28672f81caabc41.
Revert "Removed workaround for ancient GCC bug. If you're using a version that old, you should expect bugs. No reason to clutter the makefile."

This reverts commit 27bccd838d8929cfc370fddec99a815a13280ae7.