Add a SANITIZE_HOST flag.

We had discussed the idea of making all host tools default to using
ASAN. Even if we don't make it the default, this makes it easy for the
user to switch all host binaries over.

Change-Id: I64a5c741b1b4e9aefed3a6be8dcd4f386e06b29c
diff --git a/envsetup.sh b/envsetup.sh
index 0e853fe..9a540ef 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -17,6 +17,11 @@
 - sgrep:   Greps on all local source files.
 - godir:   Go to the directory containing a file.
 
+Environemnt options:
+- SANITIZE_HOST: Set to 'true' to use ASAN for all host modules. Note that
+                 ASAN_OPTIONS=detect_leaks=0 will be set by default until the
+                 build is leak-check clean.
+
 Look at the source to view more functions. The complete list is:
 EOF
     T=$(gettop)
@@ -231,6 +236,7 @@
     export ANDROID_BUILD_TOP=$(gettop)
     # With this environment variable new GCC can apply colors to warnings/errors
     export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'
+    export ASAN_OPTIONS=detect_leaks=0
 }
 
 function set_sequence_number()