Corrected implementation of @X@_base_inv_a2_check to be compliant with NVECTOR behavior

base/modules/serial/psb_c_base_vect_mod.f90

@@ -1523,7 +1523,7 @@ contains
           y%v(i) = 1_psb_spk_/x(i)
         else
           info = 1
-          exit
+          y%v(i) = 0_psb_spk_
         end if
       end do
     end if

base/modules/serial/psb_d_base_vect_mod.f90

@@ -1530,7 +1530,7 @@ contains
           y%v(i) = 1_psb_dpk_/x(i)
         else
           info = 1
-          exit
+          y%v(i) = 0_psb_dpk_
         end if
       end do
     end if

base/modules/serial/psb_s_base_vect_mod.f90

@@ -1530,7 +1530,7 @@ contains
           y%v(i) = 1_psb_spk_/x(i)
         else
           info = 1
-          exit
+          y%v(i) = 0_psb_spk_
         end if
       end do
     end if

base/modules/serial/psb_z_base_vect_mod.f90

@@ -1523,7 +1523,7 @@ contains
           y%v(i) = 1_psb_dpk_/x(i)
         else
           info = 1
-          exit
+          y%v(i) = 0_psb_dpk_
         end if
       end do
     end if