[api] Assume that v8/include is in the include path for all public headers

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 73472ba5babff7ff1f827c9db1e4028afc139a8c..34ea9ee4f976900e7af1280fc2fbfc485a3f6a13 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -77,6 +77,11 @@ config("internal_config_base") {
   include_dirs = [ "." ]
 }
 
+# This config should be applied to code using the libplatform.
+config("libplatform_config") {
+  include_dirs = [ "include" ]
+}
+
 # This config should only be applied to code using V8 and not any V8 code
 # itself.
 config("external_config") {
@@ -1842,6 +1847,7 @@ if (current_toolchain == snapshot_toolchain) {
     configs += [ "//build/config/compiler:no_chromium_code" ]
     configs += [
       ":internal_config",
+      ":libplatform_config",
       ":features",
       ":toolchain",
     ]
@@ -1954,6 +1960,7 @@ source_set("json_fuzzer") {
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [
     ":internal_config",
+    ":libplatform_config",
     ":features",
     ":toolchain",
   ]
@@ -1972,6 +1979,7 @@ source_set("parser_fuzzer") {
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [
     ":internal_config",
+    ":libplatform_config",
     ":features",
     ":toolchain",
   ]
@@ -1990,6 +1998,7 @@ source_set("regexp_fuzzer") {
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [
     ":internal_config",
+    ":libplatform_config",
     ":features",
     ":toolchain",
   ]