[epiphany] HACKING.md: add Malloc=1 to valgrind instructions

[Michael Catanzaro <mcatanzaro src gnome org>]

commit dfcdce699c1b7091670904f72282b79cf154be20
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Wed May 13 01:19:16 2020 +0000

    HACKING.md: add Malloc=1 to valgrind instructions
    
    Probably a good idea to disable bmalloc entirely when valgrinding.

 HACKING.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/HACKING.md b/HACKING.md
index 0d1b73791..038711d67 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -214,5 +214,5 @@ To use valgrind, you must use environment variables to disable WebKit's sandbox
 and JavaScriptCore's Gigacage:
 
 ```
-WEBKIT_FORCE_SANDBOX=0 GIGACAGE_ENABLED=0 G_SLICE=always-malloc valgrind --track-origins=yes 
--leak-check=full epiphany
+WEBKIT_FORCE_SANDBOX=0 GIGACAGE_ENABLED=0 G_SLICE=always-malloc Malloc=1 valgrind --track-origins=yes 
--leak-check=full epiphany
 ```