deps: histogram: unexport symbols

Fixes: nodejs/node-gyp#1755
Fixes: #27778
PR-URL: #27779
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

deps/histogram/histogram.gyp

@@ -3,6 +3,10 @@
     {
       'target_name': 'histogram',
       'type': 'static_library',
+      'cflags': ['-fvisibility=hidden'],
+      'xcode_settings': {
+        'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES',  # -fvisibility=hidden
+      },
       'include_dirs': ['src'],
       'direct_dependent_settings': {
         'include_dirs': [ 'src' ]