fix rersource leakage in sccmap

fix rersource leakage in sccmap

This addresses the following Coverity warning:

Error: RESOURCE_LEAK (CWE-772): [#def69]
graphviz-2.40.1/cmd/tools/sccmap.c:356: alloc_fn: Storage is returned from allocation function "openFile".
graphviz-2.40.1/cmd/tools/sccmap.c:313:5: alloc_fn: Storage is returned from allocation function "fopen".
graphviz-2.40.1/cmd/tools/sccmap.c:313:5: var_assign: Assigning: "fp" = "fopen(name, mode)".
graphviz-2.40.1/cmd/tools/sccmap.c:323:5: return_alloc: Returning allocated memory "fp".
graphviz-2.40.1/cmd/tools/sccmap.c:356: var_assign: Assigning: "outfp" = storage returned from "openFile(optarg, "w")".
graphviz-2.40.1/cmd/tools/sccmap.c:356: overwrite_var: Overwriting "outfp" in "outfp = openFile(optarg, "w")" leaks the storage that "outfp" points to.

Related to #1464.