[build] Fix sysroot after jessy switch

gypfiles/standalone.gypi

Index: gypfiles/standalone.gypi
diff --git a/gypfiles/standalone.gypi b/gypfiles/standalone.gypi
index 5c95f91cd23134b0ff45a9f74d7dc195bb137394..243c7966ad6a257794734d14ace2f670fd18103e 100644
--- a/gypfiles/standalone.gypi
+++ b/gypfiles/standalone.gypi
@@ -92,16 +92,16 @@
           ['OS=="linux" and use_sysroot==1', {
             'conditions': [
               ['target_arch=="arm"', {
-                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_wheezy_arm-sysroot',
+                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_jessie_arm-sysroot',
               }],
               ['target_arch=="x64"', {
-                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_wheezy_amd64-sysroot',
+                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_jessie_amd64-sysroot',
               }],
               ['target_arch=="ia32"', {
-                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_wheezy_i386-sysroot',
+                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_jessie_i386-sysroot',
               }],
               ['target_arch=="mipsel"', {
-                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_wheezy_mips-sysroot',
+                'sysroot%': '<!(cd <(DEPTH) && pwd -P)/build/linux/debian_jessie_mips-sysroot',
               }],
             ],
           }], # OS=="linux" and use_sysroot==1