Heat transfer SST tests failed without SST compilation

Created by: williamfgc

@chuckatkins this should be simple cmake level fix. ADIOS2 tries to run HeatTransfer.SST tests even with ADIOS2_USE_SST=OFF

145/145 Test #145: */TestManyVars.DontRedefineVars/* ........................................   Passed    0.12 sec

96% tests passed, 6 tests failed out of 145

Total Test time (real) =  68.98 sec

The following tests FAILED:
	 14 - HeatTransfer.SST.Dump.MxM (Failed)
	 15 - HeatTransfer.SST.Validate.MxM (Failed)
	 17 - HeatTransfer.SST.Dump.MxN (Failed)
	 18 - HeatTransfer.SST.Validate.MxN (Failed)
	 20 - HeatTransfer.SST.Dump.Mx1 (Failed)
	 21 - HeatTransfer.SST.Validate.Mx1 (Failed)
Errors while running CTest

Used configuration:

cat runconf.sh 
#!/bin/bash

cmake \
-DADIOS2_USE_SST=OFF \
-DADIOS2_USE_ADIOS1=OFF \
-DZFP_ROOT=/opt/zfp/0.5.3 \
-DSZ_ROOT=/opt/sz/2.0.2.0 \
-DCMAKE_BUILD_TYPE=Debug \
-DCMAKE_INSTALL_PREFIX=/home/wfg/tmp/adios2 \
-DADIOS2_BUILD_TESTING=ON \
-DADIOS2_BUILD_EXAMPLES=ON \
../ADIOS2;