Use 'uname -m', which in practice returns the processor architecture.

--- psm-3.3/buildflags.mak~	2014-08-20 21:00:18.000000000 +0100
+++ psm-3.3/buildflags.mak	2017-10-22 12:02:12.855291447 +0100
@@ -38,7 +38,7 @@
 endif
 
 export os ?= $(shell uname -s | tr '[A-Z]' '[a-z]')
-export arch := $(shell uname -p | sed -e 's,\(i[456]86\|athlon$$\),i386,')
+export arch := $(shell uname -m | sed -e 's,\(i[456]86\|athlon$$\),i386,')
 
 CC ?= gcc
 
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<tr><td><span title='2021-10-14 00:24:34 +0200'>2021-10-14</span></td><td><a href='/guix/commit/etc/git?id=f8b10932c86cf4c1657a67e8c484d76f757b64bd'>Add git configuration templates to improve diff hunk header detection.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is a follow-up to commit 9fc8ae4171e5da4939a64fc6d684c8b9d85bbe84, which
missed two hunks from &lt;https://issues.guix.gnu.org/50363&gt;.

Reported by hackeryarn on #guix.

* .gitattributes, etc/git/gitconfig: New files.

Signed-off-by: Marius Bakke &lt;marius@gnu.org&gt;
</span></span></td><td>Sarah Morgensen</td></tr>
<tr><td><span title='2020-12-14 12:15:06 -0500'>2020-12-14</span></td><td><a href='/guix/commit/etc/git?id=80ebcdd100a82fdc582e62f35042c74ce38ea753'>maint: Only run `make authenticate` when pushing commits.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/git/pre-push: Exit early when deleting a branch.
</span></span></td><td>Leo Famulari</td></tr>