Update links (mainly from http to https, fix broken links)

cmake/Modules/FindGFORTRAN.cmake

@@ -231,7 +231,7 @@ find_library(GFORTRAN NAMES gfortran
 )
 
 set_package_properties(GFORTRAN PROPERTIES
-    URL "http://gcc.gnu.org/wiki/GFortran"
+    URL "https://gcc.gnu.org/fortran/"
     DESCRIPTION "GNU Fortran library"
 )
 

cmake/Modules/FindGPSTK.cmake

@@ -80,7 +80,7 @@ else()
 endif()
 
 set_package_properties(GPSTK PROPERTIES
-    URL "http://www.gpstk.org"
+    URL "https://github.com/SGL-UT/GPSTk"
 )
 
 if(GPSTK_FOUND AND NOT ENABLE_OWN_GPSTK AND NOT TARGET Gpstk::gpstk)

cmake/Modules/FindOPENCL.cmake

@@ -15,8 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with GNSS-SDR. If not, see <https://www.gnu.org/licenses/>.
 
-#
-# This file taken from FindOpenCL project @ http://gitorious.com/findopencl
 #
 # - Try to find OpenCL
 # This module tries to find an OpenCL implementation on your system. It supports

cmake/Modules/FindUHD.cmake

@@ -104,7 +104,7 @@ if(NOT PC_UHD_VERSION)
 endif()
 
 set_package_properties(UHD PROPERTIES
-    URL "https://www.ettus.com/sdr-software/detail/usrp-hardware-driver"
+    URL "https://www.ettus.com/sdr-software/uhd-usrp-hardware-driver/"
 )
 
 if(UHD_FOUND AND UHD_VERSION)