[build] Add force_dynamic_crt option to build a static library with /MD on windows

Adds option to build a V8 library statically, but with the options on
windows that allows it to be subsequently included in another DLL. On
Windows this is required for it to correclty link against the correct
C++ runtime. Require for our Node.js shared library build.

Reference:  https://github.com/nodejs/node/pull/7487

BUG=
R=machenbach@chromium.org, michael_dawson@ca.ibm.com

Review-Url: https://codereview.chromium.org/2149963002
Cr-Commit-Position: refs/heads/master@{#37814}

gypfiles/standalone.gypi

@@ -33,6 +33,7 @@
   'includes': ['toolchain.gypi'],
   'variables': {
     'component%': 'static_library',
+    'force_dynamic_crt%': 0,
     'clang_xcode%': 0,
     # Track where uninitialized memory originates from. From fastest to
     # slowest: 0 - no tracking, 1 - track only the initial allocation site, 2

gypfiles/toolchain.gypi

@@ -1110,7 +1110,7 @@
           'VCCLCompilerTool': {
             'Optimization': '0',
             'conditions': [
-              ['component=="shared_library"', {
+              ['component=="shared_library" or force_dynamic_crt==1', {
                 'RuntimeLibrary': '3',  # /MDd
               }, {
                 'RuntimeLibrary': '1',  # /MTd
@@ -1162,7 +1162,7 @@
             'StringPooling': 'true',
             'BasicRuntimeChecks': '0',
             'conditions': [
-              ['component=="shared_library"', {
+              ['component=="shared_library" or force_dynamic_crt==1', {
                 'RuntimeLibrary': '3',  #/MDd
               }, {
                 'RuntimeLibrary': '1',  #/MTd
@@ -1353,7 +1353,7 @@
                 'FavorSizeOrSpeed': '0',
                 'StringPooling': 'true',
                 'conditions': [
-                  ['component=="shared_library"', {
+                  ['component=="shared_library" or force_dynamic_crt==1', {
                     'RuntimeLibrary': '2',  #/MD
                   }, {
                     'RuntimeLibrary': '0',  #/MT