Tests: Make function name not match SONAME

We look for `SONAME` in the output of `readelf` to check whether the
binary contains the field.  Do not provide a symbol that may
accidentally match.

Fixes: #16894

Tests/ExportImport/Export/testLibNoSONAME.c

@@ -4,7 +4,7 @@
 #define testLibNoSONAME_EXPORT
 #endif
 
-testLibNoSONAME_EXPORT int testLibNoSONAME(void)
+testLibNoSONAME_EXPORT int testLibNoSoName(void)
 {
   return 0;
 }