Put gzflags() functionality back in zutil.c.

gzflags() was put in gzwrite.c in order to be compiled exactly the
same as gzprintf(), so that it was guaranteed to return the correct
information.  However that causes a static linkage to zlib to bring
in many routines that are often not used.  All that is required to
duplicate the compilation environment of gzprintf() is to include
gzguts.h.  So that is now done in zutil.c to assure that the correct
flags are returned.

zutil.c

@@ -6,6 +6,9 @@
 /* @(#) $Id$ */
 
 #include "zutil.h"
+#ifndef Z_SOLO
+#  include "gzguts.h"
+#endif
 
 #ifndef NO_DUMMY_DECL
 struct internal_state      {int dummy;}; /* for buggy compilers */
@@ -85,11 +88,31 @@ uLong ZEXPORT zlibCompileFlags()
 #ifdef FASTEST
     flags += 1L << 21;
 #endif
-#ifdef Z_SOLO
-    return flags;
+#if defined(STDC) || defined(Z_HAVE_STDARG_H)
+#  ifdef NO_vsnprintf
+    flags += 1L << 25;
+#    ifdef HAS_vsprintf_void
+    flags += 1L << 26;
+#    endif
+#  else
+#    ifdef HAS_vsnprintf_void
+    flags += 1L << 26;
+#    endif
+#  endif
 #else
-    return flags + gzflags();
+    flags += 1L << 24;
+#  ifdef NO_snprintf
+    flags += 1L << 25;
+#    ifdef HAS_sprintf_void
+    flags += 1L << 26;
+#    endif
+#  else
+#    ifdef HAS_snprintf_void
+    flags += 1L << 26;
+#    endif
+#  endif
 #endif
+    return flags;
 }
 
 #ifdef DEBUG