Add a "long description field" to the VSC_F() macro

The intent is that they should be mined and dumped into the
documentation.

Feel free to add (or send patches with descriptions, preferably
only one line or paragraph for each.

Conflicts:

	bin/varnishd/cache_wrk.c
	include/vsc_fields.h

bin/varnishd/cache.h

@@ -219,7 +219,7 @@ struct acct {
 
 #define L0(n)
 #define L1(n)			uint64_t n;
-#define VSC_F(n, t, l, f, e)	L##l(n)
+#define VSC_F(n, t, l, f, e,d)	L##l(n)
 #define VSC_DO_MAIN
 struct dstat {
 #include "vsc_fields.h"

bin/varnishd/cache_pool.c

@@ -94,7 +94,7 @@ wrk_sumstat(struct worker *w)
 #define L0(n)
 #define L1(n) (VSC_C_main->n += w->stats.n)
 #define VSC_DO_MAIN
-#define VSC_F(n, t, l, f, d) L##l(n);
+#define VSC_F(n, t, l, f, d, e) L##l(n);
 #include "vsc_fields.h"
 #undef VSC_F
 #undef VSC_DO_MAIN

include/vsc.h

@@ -38,7 +38,7 @@
 #define VSC_TYPE_VBE	"VBE"
 #define VSC_TYPE_LCK	"LCK"
 
-#define VSC_F(n, t, l, f, e)	t n;
+#define VSC_F(n, t, l, f, e, d)	t n;
 
 #define VSC_DO(u,l,t) struct VSC_C_##l {
 #define VSC_DONE(u,l,t) };

lib/libvarnishapi/vsc.c

@@ -295,7 +295,7 @@ iter_call(const struct vsc *vsc, VSC_iter_f *func, void *priv,
 		sp.class = t;						\
 		sp.ident = sha->ident;
 
-#define VSC_F(nn,tt,ll,ff,dd)						\
+#define VSC_F(nn,tt,ll,ff,dd,ee)					\
 		sp.name = #nn;						\
 		sp.fmt = #tt;						\
 		sp.flag = ff;						\
@@ -331,7 +331,7 @@ VSC_Iter(struct VSM_data *vd, VSC_iter_f *func, void *priv)
 		if (strcmp(sha->class, VSC_CLASS))
 			continue;
 		/*lint -save -e525 -e539 */
-#define VSC_F(a,b,c,d,e)
+#define VSC_F(n,t,l,f,d,e)
 #define VSC_DONE(a,b,c)
 #define VSC_DO(U,l,t)						\
 		if (!strcmp(sha->type, t)) {			\