community/moreutils: harden setting DOCBOOKXSL a bit

In the future we should remove the patch entirely.

community/moreutils/APKBUILD

@@ -15,7 +15,11 @@ source="http://ftp.de.debian.org/debian/pool/main/m/moreutils/moreutils_$pkgver.
 	docbook-xsl.patch"
 
 build() {
-	make
+	_docbookpath="$(echo /usr/share/xml/docbook/xsl-stylesheets-*)"
+	if [ -z "$_docbookpath" ]; then
+		error "Couldn't get $_docbookpath, you need docbook-xsl installed"
+	fi
+	make DOCBOOKXSL=$_docbookpath
 }
 
 check() {
@@ -31,4 +35,4 @@ package() {
 }
 
 sha512sums="71bd5ec4d265dff708db372189146acb067c4edaf62888755d245ccb3f4b5bb54f6c31bda68991f78c27ab231de8ea7126f947834f3604b60d7142d0357cb66b  moreutils_0.63.orig.tar.xz
-6175a6ddad44d3a27305982b9637e2551b1269a84db9cd62f72970a85410970f875e44d97d96a77f1583ace4abf93455209c17bb054e38dbf11d21a95557592e  docbook-xsl.patch"
+4e55b2f45443c71dcf3ff99f233119b997e52d4979985ff5269c07d98bb6ddcee74658a6006165d50757beb0054a2a2cc91d46ad60b943fbd0310b318e72de99  docbook-xsl.patch"

community/moreutils/docbook-xsl.patch

@@ -1,11 +1,17 @@
---- a/Makefile	2017-02-19 20:44:09.469193976 +0100
-+++ b/Makefile	2017-02-19 20:44:32.302484346 +0100
-@@ -8,7 +8,7 @@
- ifneq (,$(findstring CYGWIN,$(shell uname)))
- 	DOCBOOKXSL?=/usr/share/sgml/docbook/xsl-stylesheets
- else
--	DOCBOOKXSL?=/usr/share/xml/docbook/stylesheet/docbook-xsl
-+	DOCBOOKXSL?=/usr/share/xml/docbook/xsl-stylesheets-1.79.2
- endif
+diff --git a/Makefile b/Makefile
+index 1e92f61..2df0af9 100644
+--- a/Makefile
++++ b/Makefile
+@@ -5,12 +5,6 @@ CFLAGS?=-O2 -g -Wall
+ INSTALL_BIN?=install -s
+ PREFIX?=/usr
  
+-ifneq (,$(findstring CYGWIN,$(shell uname)))
+-	DOCBOOKXSL?=/usr/share/sgml/docbook/xsl-stylesheets
+-else
+-	DOCBOOKXSL?=/usr/share/xml/docbook/stylesheet/docbook-xsl
+-endif
+-
  DOCBOOK2XMAN=xsltproc --param man.authors.section.enabled 0 $(DOCBOOKXSL)/manpages/docbook.xsl
+ 
+ all: $(BINS) $(MANS)