Changes for UTAG compatibility with base 7.0.5 and earlier

[zioven]

While trying to build master branch at commit d6cdcbf0798e18b08bbf608e6cd5d9be68b6cf59 with EPICS base 7.0.5 I got the following error:

/usr/bin/g++  -D_GNU_SOURCE -D_DEFAULT_SOURCE         -DUSE_TYPED_RSET   -D_X86_64_  -DUNIX  -Dlinux      -O3 -g   -Wall      -mtune=generic      -m64  -I. -I../O.Common -I. -I. -I.. -I../../../include/compiler/gcc -I../../../include/os/Linux -I../../../include   -I/opt/epics7/modules/devlib2/include -I/opt/epics7/base/include/compiler/gcc -I/opt/epics7/base/include/os/Linux -I/opt/epics7/base/include     -I../../../mrfCommon/src    -c ../evrMain.cpp
/usr/bin/g++  -D_GNU_SOURCE -D_DEFAULT_SOURCE         -DUSE_TYPED_RSET   -D_X86_64_  -DUNIX  -Dlinux      -O3 -g   -Wall      -mtune=generic      -m64  -I. -I../O.Common -I. -I. -I.. -I../../../include/compiler/gcc -I../../../include/os/Linux -I../../../include   -I/opt/epics7/modules/devlib2/include -I/opt/epics7/base/include/compiler/gcc -I/opt/epics7/base/include/os/Linux -I/opt/epics7/base/include     -I../../../mrfCommon/src    -c evrtest_registerRecordDeviceDriver.cpp
/usr/bin/g++ -o evrtest  -L/home/zoven/workspace/mrfioc2/lib/linux-x86_64 -L/opt/epics7/base-7.0.5/lib/linux-x86_64 -Wl,-rpath,/home/zoven/workspace/mrfioc2/lib/linux-x86_64 -Wl,-rpath,/opt/epics7/base-7.0.5/lib/linux-x86_64           -rdynamic -m64         evrMain.o evrtest_registerRecordDeviceDriver.o    -levr -lmrfCommon -ldbRecStd -ldbCore -lca -lCom
evrtest_registerRecordDeviceDriver.o: In function `__static_initialization_and_destruction_0':
/home/zoven/workspace/mrfioc2/evrApp/src/O.linux-x86_64/evrtest_registerRecordDeviceDriver.cpp:195: undefined reference to `pvar_dset_devI64OEventUtagEVR'
collect2: error: ld returned 1 exit status
make[3]: *** [evrtest] Error 1
make[3]: Leaving directory `/home/zoven/workspace/mrfioc2/evrApp/src/O.linux-x86_64'
make[2]: *** [install.linux-x86_64] Error 2
make[2]: Leaving directory `/home/zoven/workspace/mrfioc2/evrApp/src'
make[1]: *** [src.install] Error 2
make[1]: Leaving directory `/home/zoven/workspace/mrfioc2/evrApp'
make: *** [evrApp.install] Error 2

Tracing the error source pointed to the commit: 277abf2216a5f977d76ba119a19be6760a84c362

The issue is that the Makefile depends on the version of the EPICS base 7.0 and the DBR_UTAG has been added in base 7.0.6

Proposed changes provide compatibility with earlier versions of the EPICS base.