gnu: mesa: Fix build on arm architectures.

* gnu/packages/gl.scm (mesa)[inputs]: When building for an arm platform
add python-pycparser.
[arguments]: When building for aarch64 or armhf don't add kmsro as a
gallium driver.
* gnu/packages/python-xyz.scm (python-pycparser): Mark as a dependency
for mesa.

Change-Id: I61182157418a6667fcbb0d4280c959a708119b0d

gnu/packages/gl.scm

@@ -348,6 +348,10 @@ (define-public mesa
             python-pyyaml
             python-wrapper
             (@ (gnu packages base) which))
+      (if (target-arm?)
+          ;; Needed for etnaviv.
+          (list python-pycparser)
+          '())
       (if (%current-target-system)
           (list cmake-minimal-cross
                 pkg-config-for-build
@@ -362,11 +366,11 @@ (define-public mesa
          #$@(cond
              ((target-aarch64?)
               ;; This includes more drivers than "auto": asahi, r300, r600
-              '("-Dgallium-drivers=asahi,etnaviv,freedreno,kmsro,lima,\
-nouveau,panfrost,r300,r600,svga,softpipe,llvmpipe,tegra,v3d,vc4,virgl,zink"))
+              '("-Dgallium-drivers=asahi,etnaviv,freedreno,lima,nouveau,\
+panfrost,r300,r600,svga,softpipe,llvmpipe,tegra,v3d,vc4,virgl,zink"))
              ((target-arm32?)
               ;; This includes more drivers than "auto": r300, r600
-              '("-Dgallium-drivers=etnaviv,freedreno,kmsro,lima,nouveau,\
+              '("-Dgallium-drivers=etnaviv,freedreno,lima,nouveau,\
 panfrost,r300,r600,svga,softpipe,llvmpipe,tegra,v3d,vc4,virgl,zink"))
              ((or (target-ppc64le?) (target-ppc32?) (target-riscv64?))
               ;; This include more drivers than "auto": svga

gnu/packages/python-xyz.scm

@@ -10987,6 +10987,7 @@ (define-public python-pyvips
 a multithreaded image-processing system with low memory needs.")
     (license license:expat)))
 
+;; WARNING: This package is a dependency of mesa.
 (define-public python-pycparser
   (package
     (name "python-pycparser")