Bump libbpf version to 0.7

We already depend on the skeleton APIs introduced in libbpf 0.7 so
let's bump our minimum version to reflect that.

We don't enforce bpf compilation on mkosi anymore since not all
distros have sufficiently up-to-date libbpf available.

README

@@ -181,7 +181,7 @@ REQUIREMENTS:
         libcryptsetup (optional), >= 2.3.0 required for signed Verity images support
         libaudit (optional)
         libacl (optional)
-        libbpf >= 0.2.0 (optional)
+        libbpf >= 0.7.0 (optional)
         libfdisk >= 2.32 (from util-linux) (optional)
         libselinux (optional)
         liblzma (optional)

meson.build

@@ -1050,7 +1050,7 @@ want_bpf_framework = get_option('bpf-framework')
 bpf_compiler = get_option('bpf-compiler')
 bpf_framework_required = want_bpf_framework == 'true'
 
-libbpf_version_requirement = '>= 0.2.0'
+libbpf_version_requirement = '>= 0.7.0'
 if bpf_compiler == 'gcc'
         libbpf_version_requirement = '>= 1.0.0'
 endif

mkosi.build

@@ -149,7 +149,7 @@ if [ ! -f "$BUILDDIR"/build.ninja ] ; then
                 -D gnu-efi=true \
                 -D kernel-install=true \
                 -D analyze=true \
-                -D bpf-framework=true
+                -D bpf-framework=auto
 fi
 
 cd "$BUILDDIR"