checkpkg: set makepkg vars from build root to support none host archs

When building for an architecture different from the host, the correct
old package was downloaded as "$copydir"'s pacman was configured with
the target CARCH, but checkpkg doesn't know this and tries to search the
cache for host CARCH instead, producing the following error:

`==> ERROR: tarball not found for package: xxx`

This change fixes this by passing the appropriate makepkg config
explicitly, so that checkpkg behaves consistently.

Co-Authored-by: Levente Polyak <anthraxx@archlinux.org>
Signed-off-by: Levente Polyak <anthraxx@archlinux.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/doc/checkpkg.1.asciidoc b/doc/checkpkg.1.asciidoc
index 6a70dbb..d95f350 100644
--- a/doc/checkpkg.1.asciidoc
+++ b/doc/checkpkg.1.asciidoc
@@ -29,6 +29,9 @@ Options
 *-w, --warn*::
 	Print a warning instead of a regular message in case of soname differences.
 
+*-M, --makepkg-config*::
+	Set an alternate makepkg configuration file.
+
 *-h, --help*::
 	Show a help text