Fixed cmake downloading script

dlib/travis/get-old-cmakes.sh

@@ -3,15 +3,11 @@
 # Exit if anything fails.
 set -eux
 
-## download CMAKE to get colored output
-if [[ ! -x cmake/3.5/bin/cmake && -d cmake ]]; then
+if [[ ! -x cmake/2.8/bin/cmake || ! -x cmake/3.1/bin/cmake || ! -x cmake/3.5/bin/cmake ]]; then
     rm -rf cmake
 fi
-if [[ ! -d cmake ]]; then
-  CMAKE_URL="http://www.cmake.org/files/v3.5/cmake-3.5.2-Linux-x86_64.tar.gz"
-  mkdir -p cmake/3.5
-  wget --no-check-certificate -O - ${CMAKE_URL} | tar --strip-components=1 -xz -C cmake/3.5
 
+if [[ ! -d cmake ]]; then
   CMAKE_URL="http://www.cmake.org/files/v2.8/cmake-2.8.12-Linux-i386.tar.gz"
   mkdir -p cmake/2.8
   wget --no-check-certificate -O - ${CMAKE_URL} | tar --strip-components=1 -xz -C cmake/2.8
@@ -19,4 +15,9 @@ if [[ ! -d cmake ]]; then
   CMAKE_URL="http://www.cmake.org/files/v3.1/cmake-3.1.2-Linux-x86_64.tar.gz"
   mkdir -p cmake/3.1
   wget --no-check-certificate -O - ${CMAKE_URL} | tar --strip-components=1 -xz -C cmake/3.1
+
+  CMAKE_URL="http://www.cmake.org/files/v3.5/cmake-3.5.2-Linux-x86_64.tar.gz"
+  mkdir -p cmake/3.5
+  wget --no-check-certificate -O - ${CMAKE_URL} | tar --strip-components=1 -xz -C cmake/3.5
+
 fi