Don't double-pointer and then assign from single-pointer
Fixes compilation with GCC-15
https://bugs.gentoo.org/920312
--- a/common/savefile.c
+++ b/common/savefile.c
@@ -152,7 +152,7 @@
 			fclose(fp);
 		}
 		if (s->is_a_FILE) {
-			s->fp = (gzFile *)fopen(s->name, "a");
+			s->fp = (gzFile)fopen(s->name, "a");
 		} else {
 			s->fp = gzopen(s->name, "a");
 			s->isCompressed = 1;
--- a/include/msieve.h
+++ b/include/msieve.h
@@ -101,7 +101,7 @@
 	uint32 read_size;
 	uint32 eof;
 #else
-	gzFile *fp;
+	gzFile fp;
 	char isCompressed;
 	char is_a_FILE;
 #endif