[v15] Enhance library dependency management with libelf check (#44019)

* Enhance library dependency management with libelf check

Added logic to check for libelf presence and use pkgconf to dynamically include necessary static libraries when available. If libelf is not found, default to manually specified -lelf and -lz libraries. This ensures more reliable builds across different environments and addresses issues with Ubuntu 24.04.

* Remove duplicated pkgconf library

common.mk

@@ -40,7 +40,29 @@ ER_BPF_BUILDDIR := lib/bpf/bytecode
 CLANG_BPF_SYS_INCLUDES = $(shell $(CLANG) -v -E - </dev/null 2>&1 \
 	| sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }')
 
-STATIC_LIBS += -L/usr/libbpf-${LIBBPF_VER}/lib64/ -lbpf -lelf -lz
+# Include libbpf dependency. We don't use pkg-config here because we use specific version of libbpf
+# and we don't want to include the system libbpf.
+STATIC_LIBS += -L/usr/libbpf-${LIBBPF_VER}/lib64/ -lbpf
+
+# Check if pkgconf is installed
+PKGCONF := $(shell which pkgconf 2>/dev/null)
+ifeq ($(PKGCONF),)
+    PKGCONF := $(shell which pkg-config 2>/dev/null)
+endif
+
+# Check if libelf is available
+HAVE_LIBELF := $(shell $(PKGCONF) --exists libelf && echo 1 || echo 0)
+
+# If pkgconf and libelf are available, use them to get the static libraries
+# and all required dependencies for the Teleport build.
+# If not, use the default libraries (libelf, libz) and hope for the best.
+# This fallback used to work until Ubuntu 24.04 which compiles with libzstd by default.
+ifeq ($(HAVE_LIBELF),1)
+    STATIC_LIBS += $(shell $(PKGCONF) --static --libs libelf)
+else
+    STATIC_LIBS += -lelf -lz
+endif
+
 # Link static version of libraries required by Teleport (bpf, pcsc) to reduce system dependencies. Avoid dependencies on dynamic libraries if we already link the static version using --as-needed.
 CGOFLAG = CGO_ENABLED=1 CGO_CFLAGS="-I/usr/libbpf-${LIBBPF_VER}/include" CGO_LDFLAGS="-Wl,-Bstatic $(STATIC_LIBS) -Wl,-Bdynamic -Wl,--as-needed"
 CGOFLAG_TSH = CGO_ENABLED=1 CGO_LDFLAGS="-Wl,-Bstatic $(STATIC_LIBS_TSH) -Wl,-Bdynamic -Wl,--as-needed"