Merge pull request #241 from adrifoster/buildlib_fix

Simple fix for buildlib python bug

### Description of changes

As laid out in #240 a bug was found in the [buildlib script](https://github.com/ESCOMP/CDEPS/blob/f7e657e6f0ad2e758534b0e2cd195f18e8f08ecc/cime_config/buildlib#L182)

This code update changes the `append` line to a string concatenation and updates the `if "F90" in line and not "fox" in line:` line to ensure different capitalizations of "fox" don't slip through.


Contributors other than yourself, if any: @billsacks 

CDEPS Issues Fixed (include github issue #): #240

Are there dependencies on other component PRs (if so list): No

Are changes expected to change answers (bfb, different to roundoff, more substantial): No

Any User Interface Changes (namelist or namelist defaults changes): No

Testing performed (e.g. aux_cdeps, CESM prealpha, etc):

Tested manually with `SMS_D_Ld1_P8x1.f10_f10_mg37.I2000Clm50BgcCropQianRs.fleabone_gnu.clm-default` (on personal computer)

Hashes used for testing:
`cdeps1.0.13-1-gd31de60`

cime_config/buildlib

@@ -178,8 +178,8 @@ def buildlib(bldroot, libroot, case):
         # Do not allow any warnings except from fox external
         nextline = ""
         for line in e.split("\n"):
-            if "F90" in line and not "fox" in line:
-                nextline.append(line)
+            if "f90" in line.lower() and not "fox" in line.lower():
+                nextline = nextline + line
         if len(nextline) > 0:
             expect(False, nextline)