bionic: use jemalloc by default and allow opt-in to scudo (3/4)

Overall, jemalloc performs 23.4% better than Scudo while consuming
1.7% less amount of memory in system/extra's real-world memory_replay
traces:

https://docs.google.com/spreadsheets/d/19wLanILSw_l2d7oot3VvcZiFSLzPRWNb_a5ZyA3aFSU/edit?usp=sharing

Scudo performs fairly well for a hardened memory allocator, but we're
optimizing for performance.

Tests were performed by statically linking memory_replay under QSSI 14.
Android userspace has been stopped before performing all benchmarks,
and each test was executed 10 times with an idle detector in between to
reduce noise and errors.

The entire test took about 3 days:
https://github.com/arter97/android_memory_replay_helper

This commit has been inspired from ProtonAOSP/android_bionic@b220489

Change-Id: I5f6955bac87d87f9ef931c9be2fd43ac5d8fbcd7
Signed-off-by: Juhyung Park <qkrwngud825@gmail.com>

Author: arter97

libc/Android.bp

@@ -125,7 +125,7 @@ cc_defaults {
         malloc_pattern_fill_contents: {
             cflags: ["-DSCUDO_PATTERN_FILL_CONTENTS"],
         },
-        malloc_not_svelte: {
+        malloc_use_scudo: {
             cflags: ["-DUSE_SCUDO"],
         },
     },
@@ -136,7 +136,7 @@ cc_defaults {
 }
 
 libc_scudo_product_variables = {
-    malloc_not_svelte: {
+    malloc_use_scudo: {
         cflags: ["-DUSE_SCUDO"],
         whole_static_libs: ["libscudo"],
         exclude_static_libs: [
@@ -148,9 +148,6 @@ libc_scudo_product_variables = {
 
 // Defaults for native allocator libs/includes to make it
 // easier to change.
-// To disable scudo for the non-svelte config remove the line:
-//     product_variables: libc_scudo_product_variables,
-// in the cc_defaults below.
 // ========================================================
 cc_defaults {
     name: "libc_native_allocator_defaults",