mesa-pvr: add dynamic-layer append for llvmpipe

Meta-clang provides a bbappend for mesa to use clang to accelerate it's
rasterization with runtime code generation through the use of llvmpipe.
With the addition of mesa-pvr we no longer get this for free with the
blanket mesa bbappend on the devices that explicitly request mesa-pvr so
lets add a dynamic layer to append the same args meta-clang does.

Though the number of devices that would select pvr-mesa and still want
to use software rendering is small, it's not zero due to debug and
testing purposes.

Signed-off-by: Randolph Sapp <rs@ti.com>
Signed-off-by: Ryan Eatmon <reatmon@ti.com>

meta-ti-bsp/conf/layer.conf

@@ -18,6 +18,10 @@ LAYERDEPENDS_meta-ti-bsp = " \
     meta-arm \
 "
 
+BBFILES_DYNAMIC += " \
+    clang-layer:${LAYERDIR}/dynamic-layers/clang-layer/recipes*/*/*.bbappend \
+"
+
 SIGGEN_EXCLUDERECIPES_ABISAFE += " \
     mesa-pvr \
 "

meta-ti-bsp/dynamic-layers/clang-layer/recipes-graphics/mesa/mesa-pvr_%.bbappend

@@ -0,0 +1,14 @@
+# This is a copy of meta-clang/recipes-graphics/mesa/mesa_%.bbappend required
+# for llvmpipe when using pvr-mesa since we aren't caught by that glob.
+
+FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
+
+LDFLAGS:append:toolchain-clang = " -latomic -lm"
+DEPENDS:append:toolchain-clang = " libatomic-ops"
+
+EXTRA_OEMASON:append:toolchain-clang:x86 = " -Dasm=false"
+EXTRA_OEMASON:append:toolchain-clang:x86-64 = " -Dasm=false"
+
+export YOCTO_ALTERNATE_EXE_PATH = "${STAGING_LIBDIR}/llvm-config"
+
+PACKAGECONFIG[gallium-llvm] = "-Dllvm=true -Dshared-llvm=true -Ddraw-use-llvm=true,-Dllvm=false,clang clang-native elfutils"