gsl: drop libtool file. (This did not reach #2700...)

While at it, add cmd:pkg_config to TEST_REQUIRES as one test was
being skipped. (Now all tests succeed :)

sci-libs/gsl/gsl-2.5.recipe

@@ -50,7 +50,7 @@ COPYRIGHT="1996-2007, 2009, 2010 Gerard Jungman
 	1996, 1997, 1998, 1999, 2000, 2007 Jorma Olavi Ttinen
 	2002-2004 Jason H. Stover"
 LICENSE="GNU GPL v3"
-REVISION="1"
+REVISION="2"
 SOURCE_URI="https://ftpmirror.gnu.org/gsl/gsl-$portVersion.tar.gz
 	https://ftp.gnu.org/gnu/gsl/gsl-$portVersion.tar.gz"
 CHECKSUM_SHA256="0460ad7c2542caaddc6729762952d345374784100223995eb14d614861f2258d"
@@ -105,6 +105,10 @@ BUILD_PREREQUIRES="
 	cmd:make
 	"
 
+TEST_REQUIRES="
+	cmd:pkg_config$secondaryArchSuffix
+	"
+
 defineDebugInfoPackage gsl$secondaryArchSuffix \
 	"$commandBinDir"/gsl-histogram \
 	"$commandBinDir"/gsl-randist \
@@ -122,6 +126,8 @@ INSTALL()
 {
 	make install
 
+	rm -f "$libDir"/libgsl*.la
+
 	prepareInstalledDevelLibs libgsl libgslcblas
 	fixPkgconfig