Suppress deprecation warnings in non-clang builds too

https://codereview.chromium.org/2504463002 added suppresion of
deprecation warnings in an "if clang" block, but gcc also warns about
these, as can be seen on Chrome-Android waterfall for example. Fix
by moving the supression to an if linux||android block.

BUG=21515
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/2571433002 .

Patch from Tomasz Śniatowski <tsniatowski@opera.com>.

BUILD.gn

@@ -83,8 +83,6 @@ config("icu_code") {
   }
   if (is_clang) {
     cflags += [
-      # ICU uses its own deprecated functions.
-      "-Wno-deprecated-declarations",
       # ICU has some code with the pattern:
       #   if (found = uprv_getWindowsTimeZoneInfo(...))
       "-Wno-parentheses",
@@ -94,6 +92,12 @@ config("icu_code") {
       "-Wno-unused-function",
     ]
   }
+  if (is_clang || is_linux || is_android) {
+    cflags += [
+      # ICU uses its own deprecated functions.
+      "-Wno-deprecated-declarations",
+    ]
+  }
 }
 
 component("icui18n") {
@@ -536,14 +540,6 @@ component("icui18n") {
 
   configs += [ ":icu_code" ]
   public_configs = [ ":icu_config" ]
-
-  cflags = []
-  if (is_android || is_linux) {
-    cflags += [
-      # ICU uses its own deprecated functions.
-      "-Wno-deprecated-declarations",
-    ]
-  }
 }
 
 component("icuuc") {