Fix Arch linux dead link

Author: 0xree

doc/build-unix.md

@@ -312,7 +312,7 @@ This example lists the steps necessary to setup and build a command line only, n
 Note:
 Enabling wallet support requires either compiling against a Berkeley DB newer than 4.8 (package `db`) using `--with-incompatible-bdb`,
 or building and depending on a local version of Berkeley DB 4.8. The readily available Arch Linux packages are currently built using
-`--with-incompatible-bdb` according to the [PKGBUILD](https://projects.archlinux.org/svntogit/community.git/tree/bitcoin/trunk/PKGBUILD).
+`--with-incompatible-bdb` according to the [PKGBUILD](https://github.com/archlinux/svntogit-community/blob/packages/bitcoin/trunk/PKGBUILD).
 As mentioned above, when maintaining portability of the wallet between the standard Bitcoin Core distributions and independently built
 node software is desired, Berkeley DB 4.8 must be used.