qt: avoid LDFLAGS leaking into mkspecs

Closes #3112

srcpkgs/qt/template

@@ -1,7 +1,7 @@
 # Template file for 'qt'
 pkgname=qt
 version=4.8.7
-revision=6
+revision=7
 _distname=qt-everywhere-opensource-src
 patch_args="-Np1"
 wrksrc=${_distname}-${version}
@@ -24,11 +24,6 @@ makedepends="
 depends="qtchooser hicolor-icon-theme"
 replaces="qt-qtconfig>=0"
 
-pre_configure() {
-	sed -i "s|-O2|${CXXFLAGS}|" mkspecs/common/{g++,gcc}-base.conf
-	sed -i "/^QMAKE_LFLAGS_RPATH/s| -Wl,-rpath,||g" mkspecs/common/gcc-base-unix.conf
-	sed -i "/^QMAKE_LFLAGS\s/s|+=|+= ${LDFLAGS}|g" mkspecs/common/gcc-base.conf
-}
 do_configure() {
 	local _libdir
 
@@ -41,7 +36,10 @@ do_configure() {
 		_libdir=lib
 	fi
 
-	./configure -confirm-license -opensource \
+	QMAKE_CFLAGS="${CFLAGS}" \
+	QMAKE_CXXFLAGS="${CXXFLAGS}" \
+	QMAKE_LFLAGS="${LDFLAGS}" \
+		./configure -confirm-license -opensource \
 		-prefix /usr -sysconfdir /etc -docdir /usr/share/doc/qt \
 		-plugindir /usr/${_libdir}/qt/plugins -importdir /usr/lib/qt/imports \
 		-translationdir /usr/share/qt/translations \