[build] Disable incremental linking for cctest and unittests

gni/v8.gni

 # Copyright 2016 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/v8_target_cpu.gni")
 
 declare_args() {
   # Indicate if valgrind was fetched as a custom deps to make it available on
   # swarming.
@@ skipping 77 matching lines @@
 template("v8_executable") {
   executable(target_name) {
     forward_variables_from(invoker, "*", [ "configs" ])
     configs += invoker.configs
     configs -= v8_remove_configs
     configs += v8_add_configs
     if (is_linux) {
       # For enabling ASLR.
       ldflags = [ "-pie" ]
     }
+    if (defined(no_incremental_linking) && no_incremental_linking && is_win) {

[vogelheim, 2016/10/11 13:11:37]

I thought "defined(X) && X" was an anti-pattern that we're trying to avoid. Why
is this necessary here?

[Michael Achenbach, 2016/10/12 07:32:08]

That's how templates seem to be designed. There's no way of providing default
values. Many places in src/build actually move most fields into additional local
variables like:
https://cs.chromium.org/chromium/src/build/config/ios/rules.gni?q=template+fi...

Then we'd get the pattern:
foo = default_foo
if (defined(invoker.foo)) {
  foo = invoker.foo
}
if (foo) ...

Not sure if that's better. That's basically the same with more boilerplate.

If we want to get around the "defined" check, we'd need to write the variable in
each of the template invocations, e.g. d8, all fuzzers, etc.

See also
https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/referen...

+      configs -= [ "//build/config/win:default_incremental_linking" ]
+      configs += [ "//build/config/win:no_incremental_linking" ]
+    }
   }
 }
 
 template("v8_component") {
   component(target_name) {
     forward_variables_from(invoker, "*", [ "configs" ])
     configs += invoker.configs
     configs -= v8_remove_configs
     configs += v8_add_configs
   }
 }