ghostscript: add dependency for pnglibconf.h

When using parallel make jobs, we need to be sure that
pnglibconf.h is created before we try to reference it,
so add a rule to png.mak.

Upstream-Status: Pending

Signed-off-by: Joe Slater <jslater@windriver.com>

Rebase to 9.19
Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
---
 base/png.mak | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/base/png.mak b/base/png.mak
index fe5c6e2..8abb53a 100644
--- a/base/png.mak
+++ b/base/png.mak
@@ -74,6 +74,8 @@ png.clean-not-config-clean :
 
 pnglibconf_h=$(PNGGENDIR)$(D)pnglibconf.h
 
+$(MAKEDIRS) : $(pnglibconf_h)
+
 png.config-clean :
 	$(RM_) $(pnglibconf_h)
 	$(RM_) $(PNGGEN)lpg*.dev
-- 
2.8.1