Bug 1532899 - Mask Build tools section from about:buildconfig when …

…all it can display is "None". r=froydnj

Differential Revision: https://phabricator.services.mozilla.com/D22261

--HG--
extra : moz-landing-system : lando

toolkit/content/buildconfig.html

@@ -31,6 +31,7 @@ <h2>Build platform</h2>
     </tr>
   </tbody>
 </table>
+#if defined(CC) && defined(CXX) && defined(RUSTC)
 <h2>Build tools</h2>
 <table>
   <tbody>
@@ -56,6 +57,7 @@ <h2>Build tools</h2>
     </tr>
   </tbody>
 </table>
+#endif
 <h2>Configure options</h2>
 <p>@MOZ_CONFIGURE_OPTIONS@</p>
 #ifdef ANDROID

toolkit/content/moz.build

@@ -6,8 +6,11 @@
 
 TEST_DIRS += ['tests']
 
-for var in ('target', 'MOZ_CONFIGURE_OPTIONS', 'CC', 'CC_VERSION', 'CXX',
-            'RUSTC', 'RUSTC_VERSION'):
+for var in ('CC', 'CC_VERSION', 'CXX', 'RUSTC', 'RUSTC_VERSION'):
+    if CONFIG[var]:
+        DEFINES[var] = CONFIG[var]
+
+for var in ('target', 'MOZ_CONFIGURE_OPTIONS'):
     DEFINES[var] = CONFIG[var]
 
 DEFINES['CFLAGS'] = ' '.join(CONFIG['OS_CFLAGS'])