Add pahole during build

add pahole add-on during build to
allow kernel with BPF/BTF enabled
to be built. no need to install pahole
since we only need it during build.

the procedure to prepare pahole tar ball:

download pahole from [0]
untar it and download libbpf from [1]
and untar libbpf

then:

rm pahole-1.25/lib/bpf
mv libbpf-1.3.0 to pahole-1.25/lib/
cd pahole-1.25/lib/
mv libbpf-1.3.0 bpf
cd ../../
tar -czcf pahole-1.25.tar.gz pahole-1.25

mv pahole-1.25.tar.gz ipfire-2.x/cache
b2sum ipfire-2.x/cache/pahole-1.25.tar.gz

Note cmake without optimization -O2 in
lfs/pahole result in _FORTIFY_SOURCE requires
optimzation error since ipfire glibc built
with --enable-fortify-source

this also avoid the hack in [2]

[0]https://git.kernel.org/pub/scm/devel/pahole/pahole.git/snapshot/pahole-1.25.tar.gz
[1]https://github.com/libbpf/libbpf/archive/refs/tags/v1.3.0.tar.gz
[2]https://community.ipfire.org/t/how-to-customize-config-kernel-kernel-config-x86-64-ipfire/11100/8

Signed-off-by: Vincent Li <vincent.mc.li@gmail.com>

lfs/pahole

@@ -0,0 +1,78 @@
+###############################################################################
+#                                                                             #
+# IPFire.org - A linux based firewall                                         #
+# Copyright (C) 2007-2023  IPFire Team  <info@ipfire.org>                     #
+#                                                                             #
+# This program is free software: you can redistribute it and/or modify        #
+# it under the terms of the GNU General Public License as published by        #
+# the Free Software Foundation, either version 3 of the License, or           #
+# (at your option) any later version.                                         #
+#                                                                             #
+# This program is distributed in the hope that it will be useful,             #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of              #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
+# GNU General Public License for more details.                                #
+#                                                                             #
+# You should have received a copy of the GNU General Public License           #
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
+#                                                                             #
+###############################################################################
+
+###############################################################################
+# Definitions
+###############################################################################
+
+include Config
+
+VER        = 1.25
+
+THISAPP    = pahole-$(VER)
+DL_FILE    = $(THISAPP).tar.gz
+DL_FROM    = $(URL_IPFIRE)
+DIR_APP    = $(DIR_SRC)/$(THISAPP)
+TARGET     = $(DIR_INFO)/$(THISAPP)
+
+###############################################################################
+# Top-level Rules
+###############################################################################
+
+objects = $(DL_FILE)
+
+$(DL_FILE) = $(DL_FROM)/$(DL_FILE)
+
+$(DL_FILE)_BLAKE2 = dc608dc6b689b3f243cd7349b83e4d6f7b641f99c8c182920a05c4fec396390ae3d3349d65d50724d1c9ee1eab2748b2d6fb05f59231f28c538c9a545ae63c09
+
+install : $(TARGET)
+
+check : $(patsubst %,$(DIR_CHK)/%,$(objects))
+
+download :$(patsubst %,$(DIR_DL)/%,$(objects))
+
+b2 : $(subst %,%_BLAKE2,$(objects))
+
+###############################################################################
+# Downloading, checking, b2sum
+###############################################################################
+
+$(patsubst %,$(DIR_CHK)/%,$(objects)) :
+	@$(CHECK)
+
+$(patsubst %,$(DIR_DL)/%,$(objects)) :
+	@$(LOAD)
+
+$(subst %,%_BLAKE2,$(objects)) :
+	@$(B2SUM)
+
+###############################################################################
+# Installation Details
+###############################################################################
+
+$(TARGET) : $(patsubst %,$(DIR_DL)/%,$(objects))
+	@$(PREBUILD)
+	@rm -rf $(DIR_APP) && cd $(DIR_SRC) && tar zxf $(DIR_DL)/$(DL_FILE)
+
+	cd $(DIR_APP) && mkdir build 
+	cd $(DIR_APP)/build && cmake -D__LIB=lib -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_C_FLAGS="-O2" -DCMAKE_CXX_FLAGS="-O2" ..
+	cd $(DIR_APP)/build && make && make install
+	@rm -rf $(DIR_APP)
+	@$(POSTBUILD)

make.sh

@@ -1128,6 +1128,7 @@ buildipfire() {
   lfsmake2 iproute2
   lfsmake2 screen
   lfsmake2 elfutils
+  lfsmake2 pahole
   lfsmake2 expat
   lfsmake2 libconfig
   lfsmake2 curl