v8: fix dragonflybsd build

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 87fda5cfb0e355df425fe90e0f1d31fa8fba0eb8..4c7b055b9c321592bb117f426bb7e5122f21fbc8 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -279,8 +279,7 @@
           },
         },
       }],
-      ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
-         or OS=="netbsd"', {
+      ['OS in "linux freebsd dragonflybsd openbsd solaris netbsd".split()', {
         'conditions': [
           [ 'v8_no_strict_aliasing==1', {
             'cflags': [ '-fno-strict-aliasing' ],
@@ -290,8 +289,8 @@
       ['OS=="solaris"', {
         'defines': [ '__C99FEATURES__=1' ],  # isinf() etc.
       }],
-      ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
-         or OS=="netbsd" or OS=="mac" or OS=="android") and \
+      ['(OS=="linux" or OS=="freebsd" or OS=="dragonflybsd" or OS=="openbsd" \
+         or OS=="solaris" or OS=="netbsd" or OS=="mac" or OS=="android") and \
         (v8_target_arch=="arm" or v8_target_arch=="ia32" or \
          v8_target_arch=="mipsel")', {
         # Check whether the host compiler and target compiler support the
@@ -324,7 +323,7 @@
           }],
         ],
       }],
-      ['OS=="freebsd" or OS=="openbsd"', {
+      ['OS=="freebsd" or OS=="dragonflybsd" or OS=="openbsd"', {
         'cflags': [ '-I/usr/local/include' ],
       }],
       ['OS=="netbsd"', {
@@ -363,7 +362,7 @@
           ['v8_enable_extra_checks==1', {
             'defines': ['ENABLE_EXTRA_CHECKS',],
           }],
-          ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd"', {
+          ['OS in "linux freebsd dragonflybsd openbsd netbsd".split()', {
             'cflags': [ '-Wall', '<(werror)', '-W', '-Wno-unused-parameter',
                         '-Wnon-virtual-dtor', '-Woverloaded-virtual' ],
           }],
@@ -391,8 +390,8 @@
           ['v8_enable_extra_checks==1', {
             'defines': ['ENABLE_EXTRA_CHECKS',],
           }],
-          ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd" \
-            or OS=="android"', {
+          ['OS=="linux" or OS=="freebsd" or OS=="dragonflybsd" \
+            or OS=="openbsd" or OS=="netbsd" or OS=="android"', {
             'cflags!': [
               '-O2',
               '-Os',