graphics/pdf2djvu: unbreak for poppler 20.12

Hi,

the pdf2djvu configure script performs checks against poppler-splash,
but poppler-splash.pc had been removed in poppler-20.12. Check against
poppler itself to unbreak the build.

No bump required, because nothing except the configure checks changes.

ok?

Ciao,
Kili

Index: patches/patch-configure
===================================================================
RCS file: patches/patch-configure
diff -N patches/patch-configure
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-configure 7 Dec 2020 00:46:56 -0000
@@ -0,0 +1,75 @@
+$OpenBSD$
+
+Let it build with poppler-20.12.
+
+Index: configure
+--- configure.orig
++++ configure
+@@ -4006,19 +4006,19 @@ $as_echo "ok" >&6; }
+
+
+ pkg_failed=no
+-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for poppler-splash >= 0.35.0" >&5
+-$as_echo_n "checking for poppler-splash >= 0.35.0... " >&6; }
++{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for poppler >= 0.35.0" >&5
++$as_echo_n "checking for poppler >= 0.35.0... " >&6; }
+
+ if test -n "$POPPLER_CFLAGS"; then
+ pkg_cv_POPPLER_CFLAGS="$POPPLER_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+ if test -n "$PKG_CONFIG" && \
+- { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"poppler-splash >= 0.35.0\""; } >&5
+- ($PKG_CONFIG --exists --print-errors "poppler-splash >= 0.35.0") 2>&5
++ { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"poppler >= 0.35.0\""; } >&5
++ ($PKG_CONFIG --exists --print-errors "poppler >= 0.35.0") 2>&5
+ ac_status=$?
+ $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+ test $ac_status = 0; }; then
+- pkg_cv_POPPLER_CFLAGS=`$PKG_CONFIG --cflags "poppler-splash >= 0.35.0" 2>/dev/null`
++ pkg_cv_POPPLER_CFLAGS=`$PKG_CONFIG --cflags "poppler >= 0.35.0" 2>/dev/null`
+ test "x$?" != "x0" && pkg_failed=yes
+ else
+ pkg_failed=yes
+@@ -4030,12 +4030,12 @@ if test -n "$POPPLER_LIBS"; then
+ pkg_cv_POPPLER_LIBS="$POPPLER_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+ if test -n "$PKG_CONFIG" && \
+- { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"poppler-splash >= 0.35.0\""; } >&5
+- ($PKG_CONFIG --exists --print-errors "poppler-splash >= 0.35.0") 2>&5
++ { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"poppler >= 0.35.0\""; } >&5
++ ($PKG_CONFIG --exists --print-errors "poppler >= 0.35.0") 2>&5
+ ac_status=$?
+ $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+ test $ac_status = 0; }; then
+- pkg_cv_POPPLER_LIBS=`$PKG_CONFIG --libs "poppler-splash >= 0.35.0" 2>/dev/null`
++ pkg_cv_POPPLER_LIBS=`$PKG_CONFIG --libs "poppler >= 0.35.0" 2>/dev/null`
+ test "x$?" != "x0" && pkg_failed=yes
+ else
+ pkg_failed=yes
+@@ -4056,14 +4056,14 @@ else
+ _pkg_short_errors_supported=no
+ fi
+ if test $_pkg_short_errors_supported = yes; then
+- POPPLER_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "poppler-splash >= 0.35.0" 2>&1`
++ POPPLER_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "poppler >= 0.35.0" 2>&1`
+ else
+- POPPLER_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "poppler-splash >= 0.35.0" 2>&1`
++ POPPLER_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "poppler >= 0.35.0" 2>&1`
+ fi
+ # Put the nasty error message in config.log where it belongs
+ echo "$POPPLER_PKG_ERRORS" >&5
+
+- as_fn_error $? "Package requirements (poppler-splash >= 0.35.0) were not met:
++ as_fn_error $? "Package requirements (poppler >= 0.35.0) were not met:
+
+ $POPPLER_PKG_ERRORS
+
+@@ -4095,7 +4095,7 @@ else
+ $as_echo "yes" >&6; }
+
+ fi
+-poppler_version=$($PKG_CONFIG --modversion poppler-splash)
++poppler_version=$($PKG_CONFIG --modversion poppler)
+
+ cat >>confdefs.h <<_ACEOF
+ #define POPPLER_VERSION_STRING "$poppler_version"