scripted-diff: Use bpf_cflags

-BEGIN VERIFY SCRIPT-

 ren() { sed --regexp-extended -i "s/$1/$2/g" $( git grep --extended-regexp -l "$1" ) ; }

 ren 'cflags=\["-Wno-error=implicit-function-declaration"\]' 'cflags=bpf_cflags()'

-END VERIFY SCRIPT-

test/functional/interface_usdt_validation.py

@@ -99,7 +99,7 @@ class ValidationTracepointTest(BitcoinTestFramework):
         ctx.enable_probe(probe="validation:block_connected",
                          fn_name="trace_block_connected")
         bpf = BPF(text=validation_blockconnected_program,
-                  usdt_contexts=[ctx], debug=0, cflags=["-Wno-error=implicit-function-declaration"])
+                  usdt_contexts=[ctx], debug=0, cflags=bpf_cflags())
 
         def handle_blockconnected(_, data, __):
             event = ctypes.cast(data, ctypes.POINTER(Block)).contents