[Variadic] Generate functions at original loc (not call loc)

src/plugins/e-acsl/tests/builtin/oracle_ci/gen_strcmp.c

...ns/e-acsl/tests/special/oracle_ci/gen_e-acsl-instrument.c

src/plugins/variadic/standard.ml

src/plugins/variadic/tests/known/oracle/snprintf.res.oracle

src/plugins/variadic/tests/known/oracle/swprintf.res.oracle

tests/idct/oracle/ieee_1180_1990.res.oracle