Dont output line numbers before they were set first

The first lines of an xpp preprocessed file contain stuff from include
files; prominently `lib/sysruk.x`. Here, xpp does not issue line
numbers.

This patch prevents rpp from printing (wrong) linenumbers and the
wrong input file.

unix/boot/spp/rpp/rppfor/ngetch.f

@@ -81,6 +81,7 @@ integer function ngetch (c)
       linect (level) = n - 1
 23006 continue
 23004 continue
+      if (.not.(linect (level) .gt. 0))goto23003
       linect (level) = linect (level) + 1
 23003 continue
       goto 23001

unix/boot/spp/rpp/rppfor/outdon.f

@@ -67,7 +67,8 @@ subroutine outdon
       data sline0(1)/35/,sline0(2)/108/,sline0(3)/105/,sline0(4)/110/,sl
      *ine0(5)/101/,sline0(6)/32/,sline0(7)/-2/
       if (.not.(dbgout .eq. 1))goto 23000
-      if (.not.(body .eq. 1 .or. dbglev .ne. level))goto 23002
+      if (.not.((body .eq. 1 .or. dbglev .ne. level)
+     * .and. linect (level) .gt. 0))goto 23002
       op = 1
       ip=1
 23004 if (.not.(sline0(ip) .ne. -2))goto 23006

unix/boot/spp/rpp/rpprat/ngetch.r

@@ -23,7 +23,9 @@
 	       linect (level) = n - 1
 	       }
 	    }
-	 linect (level) = linect (level) + 1
+	    if (linect (level) > 0) {
+	       linect (level) = linect (level) + 1
+	    }
 	 }
    else {
       c = buf (bp)

unix/boot/spp/rpp/rpprat/outdon.r

@@ -13,7 +13,7 @@
 
     # If dbgout is enabled output the "#line" statement.
     if (dbgout == YES) {
-	if (body == YES | dbglev != level) {
+	if ((body == YES | dbglev != level) & linect (level) > 0) {
 	    op = 1
 	    for (ip=1;  s_line(ip) != EOS;  ip=ip+1) {
 		obuf(op) = s_line(ip)