store fft wisdom files in writable /ioc/data

startup.script_common

@@ -16,6 +16,9 @@ putenv "SRBASE=/ioc/data"
 sprintf STRINGBUFFER, "EPICS_DRIVER_PATH=.:bin/%s_%s:bin:snl:../bin:%s", EPICS, EPICS_HOST_ARCH, EPICS_MODULES
 putenv STRINGBUFFER
 
+sprintf STRINGBUFFER, "FFT_WISDOM_DIR=/ioc/data/%s", IOC
+putenv STRINGBUFFER
+
 STREAM_PROTOCOL_DIR=malloc(80)
 sprintf STREAM_PROTOCOL_DIR, "%s/cfg", HOME