[sr-dev] compiler warnings (latest master)

CC (gcc) [M pv.so] pv_core.o pv_core.c: In function 'pv_get_hdrc': pv_core.c:1811:9: warning: unused variable 'p_size' [-Wunused-variable] int n, p_size; ^ pv_core.c:1811:6: warning: unused variable 'n' [-Wunused-variable] int n, p_size; ^ pv_core.c:1810:12: warning: unused variable 'p_ini' [-Wunused-variable] char *p, *p_ini; ^ pv_core.c:1810:8: warning: unused variable 'p' [-Wunused-variable] char *p, *p_ini; ^ pv_core.c:1809:20: warning: unused variable 'hf0' [-Wunused-variable] struct hdr_field *hf0; ^ pv_core.c:1806:6: warning: unused variable 'idxf' [-Wunused-variable] int idxf; ^ pv_core.c:1805:6: warning: unused variable 'idx' [-Wunused-variable] int idx; ^