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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<div class='path'>path: <a href='/guix/log/?id=6c0131b37537d57015336dd97637ab98a5ec036b'>root</a>/<a href='/guix/log/tests?id=6c0131b37537d57015336dd97637ab98a5ec036b'>tests</a>/<a href='/guix/log/tests/build-utils.scm?id=6c0131b37537d57015336dd97637ab98a5ec036b'>build-utils.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/build-utils.scm?id=6c0131b37537d57015336dd97637ab98a5ec036b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-11-26 00:16:35 +0100'>2019-11-26</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=f5698dfb87df1132ca5c73a8ed7f75f63c07669f'>tests: Avoid unnecessary use of 'mock'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/build-utils.scm ("wrap-script, simple case"): Use the real
'which' instead of mocking it.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-11-26 00:16:35 +0100'>2019-11-26</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=1d64afbdc0644a2be8bd2ad157085731e212ab74'>tests: Avoid (catch 'srfi-34 …) form.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/build-utils.scm ("wrap-script, raises condition"): Use 'guard'
instead of "catch 'srfi-34".
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-06-17 16:13:36 +0200'>2019-06-17</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=45d46223f92b0933aaf9b1392a21d09eaa1e2881'>utils: Add 'invoke/quiet'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/bootloader.scm (G_): Remove.
(open-pipe-with-stderr, invoke/quiet): Move to...
* guix/build/utils.scm: ... here.  Use 'let-values' instead of
'define-values' because Guile 2.0 (the bootstrap Guile) doesn't know
about 'define-values'.
* po/guix/POTFILES.in: Remove gnu/build/bootloader.scm, and add
guix/build/utils.scm.
* tests/build-utils.scm: Remove import of (gnu build bootloader).
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-03-23 23:16:55 +0100'>2019-03-23</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=8c14f7f8a7ab0722bf4c9f92fd28ae85514d564f'>Merge branch 'staging' into core-updates</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-03-16 18:15:13 +0100'>2019-03-16</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=f0cc5e7e1e4c03af29c5d4855dc5962502c49147'>booloader: Add 'invoke/quiet'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/bootloader.scm (G_): New macro.
(open-pipe-with-stderr, invoke/quiet): New procedures.
* tests/build-utils.scm ("invoke/quiet, success")
("invoke/quiet, failure")
("invoke/quiet, failure, message on stderr"): New tests.
* po/guix/POTFILES.in: Add bootloader.scm.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-03-16 18:15:09 +0100'>2019-03-16</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=22f95e028f038cee342f455dfc55bd32b804907c'>tests: Add 'with-environment-variable'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/scripts.scm (with-environment-variable): Move to...
* guix/tests.scm (with-environment-variable): ... here.
* tests/build-utils.scm ("wrap-program, one input, multiple calls"):
Use it instead of 'setenv'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-02-08 10:26:53 +0100'>2019-02-08</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=0fb9a8df429a7b9f40610ff15baaff0d8e31e8cf'>guix: Add wrap-script.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/utils.scm (wrap-script): New procedure.
(&amp;wrap-error): New condition.
(wrap-error?, wrap-error-program, wrap-error-type): New procedures.
* tests/build-utils.scm ("wrap-script, simple case", "wrap-script, with
encoding declaration", "wrap-script, raises condition"): New tests.
</span></span></td><td>Ricardo Wurmus</td></tr>