Fix typo.

travis_install_libs.sh

+#!/bin/sh
+set -ex
+installLib() {
+	wget https://github.com/libyal/$1/releases/download/$2/$1-alpha-$2.tar.gz
+	tar -xzf $1-alpha-$2.tar.gz
+	cd $1-$2
+	if test ${TRAVIS_OS_NAME} = "linux"; then
+		./configure -prefix=/usr > /dev/null
+	else
+		./configure > /dev/null
+	fi
+	make > /dev/null && sudo make install > /dev/null
+	cd ..
+}
+
+installLib libvhdi 20181227
+installLib libvmdk 20181227
+