Xapian: bump to 1.4.7, drop hack required for 1.4.5.

The hack (to undef HAVE_EXP10 & HAVE___EXP10 in config.h) required
to fix an incorrect detection of exp10 in 1.4.5 is no longer needed.

dev-libs/xapian/xapian-1.4.7.recipe

@@ -6,11 +6,11 @@ a wide range of information retrieval-related tasks. Xapian empowers the Omega \
 search engine package. It supports a wide range of advanced features such as \
 native Unicode support and modern search algorithms."
 HOMEPAGE="https://xapian.org/"
-COPYRIGHT="1999-2017 The Xapian Authors"
+COPYRIGHT="1999-2018 The Xapian Authors"
 LICENSE="GNU GPL v2"
 REVISION="1"
 SOURCE_URI="https://oligarchy.co.uk/xapian/$portVersion/xapian-core-$portVersion.tar.xz"
-CHECKSUM_SHA256="85b5f952de9df925fd13e00f6e82484162fd506d38745613a50b0a2064c6b02b"
+CHECKSUM_SHA256="13f08a0b649c7afa804fa0e85678d693fd6069dd394c9b9e7d41973d74a3b5d3"
 SOURCE_DIR="xapian-core-$portVersion"
 
 ARCHITECTURES="!x86_gcc2 ?x86 ?x86_64"
@@ -23,7 +23,7 @@ if [ "$targetArchitecture" = x86_gcc2 ]; then
 	commandBinDir=$prefix/bin
 fi
 
-libVersion="30.4.0"
+libVersion=30.5.1
 libVersionCompat="$libVersion compat >= ${libVersion%%.*}"
 
 PROVIDES="
@@ -90,10 +90,6 @@ BUILD()
 {
 	LIBS="-lintl" \
 	runConfigure --omit-dirs binDir ./configure --bindir="$commandBinDir"
-	sed -i \
-		-e "/HAVE_EXP10/ d" \
-		-e "/HAVE___EXP10/ d" \
-		config.h
 	make $jobArgs
 }