Merge pull request #1421 from jedwards4b/hobart_nag_fix

nag compliler needs an additional library flag when built with debug

Test suite: SMS_D_Ld3.f45_g37_rx1.A.hobart_nag
Test baseline:
Test namelist changes:
Test status: bit for bit

Fixes

User interface changes?:

Code review:

config/cesm/machines/config_compilers.xml

@@ -701,6 +701,9 @@ using a fortran linker.
   <LDFLAGS>
     <append> -lpthread</append>
   </LDFLAGS>
+  <SLIBS>
+    <append> -L/usr/local/nag/lib/NAG_Fortran </append>
+  </SLIBS>
 </compiler>
 
 <compiler MACH="hobart" COMPILER="pgi">