Merge branch 'fix_ps2pdf' into 'master'

Fix failure to create .pdf files with autotools

Closes #1763

See merge request graphviz/graphviz!1577

diff --cc lib/expr/Makefile.am
index e0912a432acbe8c1a55ba5591899ede3e83240e6,03f3bd245e09eb9e24ba6ee321ba3ee651a3bdf0..260592aea5bf398e31b9df1d0bb104552385a5a4
--- 1/lib/expr/Makefile.am
--- 2/lib/expr/Makefile.am
+++ b/lib/expr/Makefile.am
@@@ -64,10 -77,11 +71,11 @@@ expr.3.pdf: expr.3.p
  
  expr.3.ps: $(srcdir)/expr.3
        @GROFF@ -Tps -man $< >$@
+ endif
  
- EXTRA_DIST = $(man_MANS) $(pdf_DATA) \
+ EXTRA_DIST = $(man_MANS) $(pdf) \
        Makefile.nmake Makefile.orig \
 -      exparse.c exparse.h exop.h \
 +      exparse.c exparse.h \
        y.tab.c y.tab.h y.output expr.vcxproj*
  
 -DISTCLEANFILES = $(pdf_DATA) exparse.[ch] exop.h y.tab.[ch] y.output expr.3.ps
 +DISTCLEANFILES = $(pdf_DATA) exparse.[ch] y.tab.[ch] y.output expr.3.ps