Make size of hypervisor heap a build parameter.

Bug: 117270899
Change-Id: Iaeb8cc2698dc8503e7c8d29098d2ab7184aa4ded
diff --git a/BUILD.gn b/BUILD.gn
index 465a20c..b0fb56f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -39,6 +39,7 @@
 
 host_toolchain("host_fake") {
   use_platform = true
+  heap_pages = 40
   max_cpus = 4
   max_vms = 6
 }
@@ -48,6 +49,7 @@
   origin_address = "0x88000000"
   use_pl011 = true
   pl011_base_address = "0x1c090000"
+  heap_pages = 40
   max_cpus = 8
   max_vms = 16
 }
@@ -57,6 +59,7 @@
   origin_address = "0x40001000"
   use_pl011 = true
   pl011_base_address = "0x09000000"
+  heap_pages = 40
   max_cpus = 8
   max_vms = 16
 }
@@ -66,6 +69,7 @@
   origin_address = "0x35000000"
   use_pl011 = true
   pl011_base_address = "0xf7113000"  # UART3
+  heap_pages = 40
   max_cpus = 8
   max_vms = 16
 }