Fix LLVM feature detection and rebuild with LLVM 21

Resolves: RHEL-148264

bpftool disassembler optionally uses LLVM to improve its capabilities.
Unfortunately, even if llvm-devel is installed, the feature detection of
LLVM doesn't work:

    Auto-detecting system features:
    ...                         clang-bpf-co-re: [ on  ]
    ...                                    llvm: [ OFF ]
    ...                                  libcap: [ on  ]
    ...                                  libbfd: [ on  ]

The reason is that the feature detection tries to compile a simple C++
program and link it against libLLVM which fails as LDFLAGS contains -pie
while CXXFLAGS does not contain -fpie.

Fix this by setting EXTRA_CXXFLAGS from the bpftool build.

Signed-off-by: Viktor Malik <vmalik@redhat.com>

.gitignore

@@ -1 +1,4 @@
 /linux-6.12.0-31.el10.tar.xz
+/linux-6.12.0-83.el10.tar.xz
+/linux-6.12.0-103.el10.tar.xz
+/linux-6.12.0-164.el10.tar.xz

bpftool.spec

@@ -4,15 +4,13 @@
 # used as kernel tar.
 
 # RHEL kernel version-release
-%define kver   6.12.0-31
+%define kver   6.12.0-164
-%define source linux-%{kver}%{?dist}
+%define kdist  .el10
+%define source linux-%{kver}%{kdist}
 
 Name:           bpftool
-Version:        7.5.0
+Version:        7.7.0
-# Currently, bpftool built from kernel uses kernel's release version.
+Release:        2%{?dist}
-# In order to do the transition smoothly, raise it to a sufficiently big number.
-# Once bpftool moves to 7.6.0, reset the release to 1.
-Release:        800%{?dist}
 Summary:        Inspection and simple manipulation of eBPF programs and maps
 
 %global libname libbpf
@@ -44,7 +42,7 @@ manipulation of eBPF programs and maps.
 # We need to use vmlinux.h from kernel-devel rather than the one from the running system
 %define kernel_version %(rpm -q --qf "%%{VERSION}-%%{RELEASE}.%%{ARCH}" kernel-devel)
 pushd tools/bpf/bpftool
-%make_build EXTRA_CFLAGS="%{build_cflags}" EXTRA_LDFLAGS="%{build_ldflags}" VMLINUX_H="/usr/src/kernels/%{kernel_version}/vmlinux.h"
+%make_build EXTRA_CFLAGS="%{build_cflags}" EXTRA_CXXFLAGS="%{build_cflags}" EXTRA_LDFLAGS="%{build_ldflags}" VMLINUX_H="/usr/src/kernels/%{kernel_version}/vmlinux.h"
 
 %install
 pushd tools/bpf/bpftool

sources

@@ -1 +1 @@
-SHA512 (linux-6.12.0-31.el10.tar.xz) = d02a04e09ec1f2f962acea2c2efe800b16e059ba8ff1aebcd905c54024772344ac30e652f5e69f82ff9739573877af0f247e751e520d29ea7b7683c658cbc83a
+SHA512 (linux-6.12.0-164.el10.tar.xz) = d2256127ae933bb822f48124f7418d2d3de44515b653fa13ad70b064a4b3662d355d2e07a44d959f33f3c6092a6200f313eb58efe02199e1db99245d506e806f