www/iridium: copy snappy fix from chromium

just like chromium (from which it was forked), iridium embeds a copy
of snappy (the compression library) and cannot be fully switched to
the system-provided archivers/snappy in an easy way. consider this a
band-aid patch

Reported by:	pkubaj
MFH:		2020Q1 (blanket: web browser, build fix)

www/iridium/files/patch-third__party_snappy_src_snappy.h

@@ -0,0 +1,20 @@
+--- third_party/snappy/src/snappy.h.orig	2020-01-22 18:43:16 UTC
++++ third_party/snappy/src/snappy.h
+@@ -73,7 +73,7 @@ namespace snappy {
+   // Original contents of *output are lost.
+   //
+   // REQUIRES: "input[]" is not an alias of "*output".
+-  size_t Compress(const char* input, size_t input_length, string* output);
++  size_t Compress(const char* input, size_t input_length, std::string* output);
+ 
+   // Decompresses "compressed[0,compressed_length-1]" to "*uncompressed".
+   // Original contents of "*uncompressed" are lost.
+@@ -82,7 +82,7 @@ namespace snappy {
+   //
+   // returns false if the message is corrupted and could not be decompressed
+   bool Uncompress(const char* compressed, size_t compressed_length,
+-                  string* uncompressed);
++                  std::string* uncompressed);
+ 
+   // Decompresses "compressed" to "*uncompressed".
+   //