NUL-terminate the SMB fileidxrec_t.name field, just in case

The terminating NUL is actually part of the index record, but with file
corruption, it's technically possible the NUL could be missing.
Fixes CID 509552

Use strnicmp() insted of stricmp() in smb_removefile()
Fixes CID 509551

src/smblib/smbfile.c

@@ -237,6 +237,7 @@ int smb_findfile(smb_t* smb, const char* filename, smbfile_t* file)
 
 		if(smb_fread(smb, &fidx, sizeof(fidx), smb->sid_fp) != sizeof(fidx))
 			break;
+		TERMINATE(fidx.name);
 
 		f->idx_offset = offset++;
 
@@ -438,7 +439,7 @@ int smb_removefile(smb_t* smb, smbfile_t* file)
 		}
 		rewind(smb->sid_fp);
 		for(uint32_t i = 0; i < smb->status.total_files; i++) {
-			if(stricmp(fidx[i].name, fname) == 0) {
+			if(strnicmp(fidx[i].name, fname, sizeof(fname) - 1) == 0) {
 				removed++;
 				continue;
 			}