browser(firefox): bundle VS C++ redistributable dlls (#4359)

browser_patches/firefox/BUILD_NUMBER

@@ -1,2 +1,2 @@
-1201
-Changed: lushnikov@chromium.org Tue 03 Nov 2020 02:16:18 PM PST
+1202
+Changed: yurys@chromium.org Thu Nov  5 20:30:30 GMTST 2020

browser_patches/firefox/build.sh

@@ -26,13 +26,22 @@ elif [[ "$(uname)" == "Linux" ]]; then
   echo "-- building on Linux"
   echo "ac_add_options --disable-av1" > .mozconfig
 elif [[ "$(uname)" == MINGW* ]]; then
+  TMPFILE=$(mktemp)
   if [[ $1 == "--win64" ]]; then
     echo "-- building win64 build on MINGW"
     echo "ac_add_options --target=x86_64-pc-mingw32" > .mozconfig
     echo "ac_add_options --host=x86_64-pc-mingw32" >> .mozconfig
+    "$PROGRAMFILES\Microsoft Visual Studio\Installer\vswhere.exe" -latest -find '**\Redist\MSVC\*\x64\**\vcruntime140.dll' > $TMPFILE
   else
     echo "-- building win32 build on MINGW"
+    "$PROGRAMFILES\Microsoft Visual Studio\Installer\vswhere.exe" -latest -find '**\Redist\MSVC\*\x86\**\vcruntime140.dll' > $TMPFILE
   fi
+  WIN32_REDIST_DIR=$(dirname "$(cat $TMPFILE)")
+  if ! [[ -d $WIN32_REDIST_DIR ]]; then
+    echo "Error: cannot find MS VS C++ redistributable $WIN32_REDIST_DIR"
+    exit 1;
+  fi
+  echo "export WIN32_REDIST_DIR=\"$WIN32_REDIST_DIR\"" >> .mozconfig
 else
   echo "ERROR: cannot upload on this platform!" 1>&2
   exit 1;