build: remove unused REFNAME macro from SANITY_CHECK

REFNAME was defined as a preprocessor macro (-DREFNAME=$(*F)f$(BU)) but
appears to have never been consumed by any source code. The SANITY_CHECK
feature uses common_reference.h which has its own independent mechanism
via BLASFUNC_REF macros with hardcoded REF_BU=f.

For context, REFNAME was imported with GotoBLAS2 in 2011 but became dead
code when the unit test framework added common_reference.h with its own
naming scheme. The CMake version also had a broken $(*F) reference that
could never work, but this was also moot since the macro was unused.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: vtjnash

Makefile.system

@@ -558,7 +558,7 @@ SANITY_CHECK = 1
 endif
 
 ifdef SANITY_CHECK
-CCOMMON_OPT	+= -DSANITY_CHECK -DREFNAME=$(*F)f$(BU)
+CCOMMON_OPT	+= -DSANITY_CHECK
 endif
 
 MAX_STACK_ALLOC ?= 2048

cmake/os.cmake

@@ -98,7 +98,6 @@ if (UTEST_CHECK)
 endif ()
 
 if (SANITY_CHECK)
-  # TODO: need some way to get $(*F) (target filename)
-  set(CCOMMON_OPT "${CCOMMON_OPT} -DSANITY_CHECK -DREFNAME=$(*F)f${BU}")
+  set(CCOMMON_OPT "${CCOMMON_OPT} -DSANITY_CHECK")
 endif ()