app-text/pdf2html: port to EAPI7

* Fix QA issues on echo calls
* Fix patches
* Use PATCHES=( )

Signed-off-by: Aaron Bauman <bman@gentoo.org>

app-text/pdf2html/files/pdf2html-1.4-gentoo.patch

@@ -1,5 +1,5 @@
---- pbm2png.c.orig	2003-09-16 20:12:55.000000000 +0900
-+++ pbm2png.c	2004-02-21 22:09:57.415786664 +0900
+--- a/pbm2png.c
++++ b/pbm2png.c
 @@ -145,15 +145,13 @@
   sprintf(string,"%s%d.html",basename,index);
   f=fopen(string,"w");

app-text/pdf2html/files/pdf2html-1.4-libpng15.patch

@@ -1,5 +1,5 @@
---- pbm2png.c
-+++ pbm2png.c
+--- a/pbm2png.c
++++ b/pbm2png.c
 @@ -23,6 +23,7 @@
  #include <stdlib.h>
  #include <string.h>

app-text/pdf2html/pdf2html-1.4.ebuild

@@ -1,8 +1,9 @@
 # Copyright 1999-2020 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
-EAPI=4
-inherit eutils toolchain-funcs
+EAPI=7
+
+inherit toolchain-funcs
 
 DESCRIPTION="Converts pdf files to html files"
 HOMEPAGE="http://atrey.karlin.mff.cuni.cz/~clock/twibright/pdf2html/"
@@ -19,22 +20,21 @@ RDEPEND="${DEPEND}
 	app-text/ghostscript-gpl
 	>=media-gfx/imagemagick-6"
 
-src_prepare() {
-	epatch \
-		"${FILESDIR}"/${P}-gentoo.patch \
-		"${FILESDIR}"/${P}-libpng15.patch
-}
+PATCHES=(
+	"${FILESDIR}"/${P}-gentoo.patch
+	"${FILESDIR}"/${P}-libpng15.patch
+)
 
 src_compile() {
 	tc-export CC
 	# Rewrite the Makefile as that's simpler
-	echo "LDLIBS=-lpng" > Makefile
-	echo "all: pbm2png" >> Makefile
+	echo "LDLIBS=-lpng" > Makefile || die "echo failed"
+	echo "all: pbm2png" >> Makefile || die "echo #2 failed"
 	emake
-	echo "pbm2eps9: pbm2eps9.o printer.o" > Makefile
+	echo "pbm2eps9: pbm2eps9.o printer.o" > Makefile || die "echo #3 failed"
 	emake pbm2eps9
 
-	echo "cp \"${EPREFIX}\"/usr/share/${P}/*.png ." >> pdf2html
+	echo "cp \"${EPREFIX}\"/usr/share/${P}/*.png ." >> pdf2html || die "echo #4 failed"
 }
 
 src_install() {