Add missing pahole dependencies

pahole is a build-time dependency of our kernel build, due to us setting
CONFIG_BTF_DEBUG_INFO. If pahole is missing, a `make modules_prepare` with our
kernel config results in symbols in the config changing. This will affect
people building kernel modules against coreos-sources in the developer
container, but not the SDK because pahole is already in sdk-depends.

pahole is now an (explicit) BDEPEND of all the coreos-kernel/coreos-modules
packages, and we'll make it an RDEPEND of coreos-sources so that it is pulled
in whenever it might be necessary.  Also add it to the coreos-dev package so
that it is included in developer container by default, uncompressed size
increase is <1MB.

sdk_container/src/third_party/coreos-overlay/changelog/bugfixes/2022-04-25-fix-dev-container-module-builds.md

@@ -0,0 +1 @@
+- Added pahole to developer container, without it kernel modules built against /usr/src/linux may fail to probe with an 'invalid relocation target' error ([PR#1839](https://github.com/flatcar-linux/coreos-overlay/pull/1839))

sdk_container/src/third_party/coreos-overlay/coreos-base/coreos-dev/coreos-dev-0.1.0.ebuild

@@ -21,6 +21,7 @@ RDEPEND="
 	coreos-base/emerge-gitclone
 	dev-lang/python
 	dev-util/strace
+	dev-util/pahole
 	dev-vcs/repo
 	net-analyzer/netperf
 	net-dialup/minicom

sdk_container/src/third_party/coreos-overlay/eclass/coreos-kernel.eclass

@@ -35,6 +35,7 @@ SLOT="0/${PVR}"
 SRC_URI=""
 IUSE=""
 
+BDEPEND="dev-util/pahole"
 DEPEND="=sys-kernel/coreos-sources-${COREOS_SOURCE_VERSION}"
 
 # Do not analyze or strip installed files

sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-sources/coreos-sources-5.15.35.ebuild

@@ -24,6 +24,9 @@ else
 	PATCH_DIR="${FILESDIR}/${KV_MAJOR}.${KV_MINOR}"
 fi
 
+# make modules_prepare depends on pahole
+RDEPEND="dev-util/pahole"
+
 KEYWORDS="amd64 arm64"
 IUSE=""