Improved error messages from atmos analysis (#1125)

The logical test used to set gsi namelist variable `nhr_obsbin` was not consistent with other checks in the script which use variable `l4densvar`.  This relocates the setting for `nhr_obsbin` to be consistent with other tests using `l4densvar`, which will allow the appropriate error messages to be output by the executable.

Fixes #1123
Fixes [NCO bugzilla #1196](http://www2.spa.ncep.noaa.gov/bugzilla/show_bug.cgi?id=1196)

scripts/exglobal_atmos_analysis.sh

@@ -537,9 +537,6 @@ $NLN $SFCGES sfcf06
 $NLN $SFCG09 sfcf09
 
 # Link hourly backgrounds (if present)
-if [ -f $ATMG04 -a -f $ATMG05 -a -f $ATMG07 -a -f $ATMG08 ]; then
-   nhr_obsbin=1
-fi
 
 [[ -f $ATMG04 ]] && $NLN $ATMG04 sigf04
 [[ -f $ATMG05 ]] && $NLN $ATMG05 sigf05
@@ -562,6 +559,7 @@ if [ $DOHYBVAR = "YES" ]; then
    fhrs="06"
    if [ $l4densvar = ".true." ]; then
       fhrs="03 04 05 06 07 08 09"
+      nhr_obsbin=1
    fi
 
    for imem in $(seq 1 $NMEM_ENKF); do