scons: Link tcmalloc_minimal by default instead of tcmalloc

tcmalloc triggers asan while tcmalloc_minimal does not. The feature
difference is not significant for regular gem5 use.

Jira issue: https://gem5.atlassian.net/browse/GEM5-1312

Change-Id: I410a26d2ecdf422c456d44276d9e7ec60582b8cc
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/67431
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>

SConstruct

@@ -609,9 +609,9 @@ for variant_path in variant_paths:
 
     if not GetOption('without_tcmalloc'):
         with gem5_scons.Configure(env) as conf:
-            if conf.CheckLib('tcmalloc'):
+            if conf.CheckLib('tcmalloc_minimal'):
                 conf.env.Append(CCFLAGS=conf.env['TCMALLOC_CCFLAGS'])
-            elif conf.CheckLib('tcmalloc_minimal'):
+            elif conf.CheckLib('tcmalloc'):
                 conf.env.Append(CCFLAGS=conf.env['TCMALLOC_CCFLAGS'])
             else:
                 warning("You can get a 12% performance improvement by "