Remove fsck_unshare_blocks.

This code is dead. It was briefly used to support "adb remount" with
deduplicated partitions, but was very quickly obsoleted by overlayfs
support. There is no reason to include it anymore.

Bug: N/A
Test: N/A
Change-Id: I4cdcbf66bec80092f954826eaae037934ff37765
diff --git a/recovery.cpp b/recovery.cpp
index e4b8e45..cbf29b6 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -45,7 +45,6 @@
 #include <ziparchive/zip_archive.h>
 
 #include "bootloader_message/bootloader_message.h"
-#include "fsck_unshare_blocks.h"
 #include "install/adb_install.h"
 #include "install/fuse_install.h"
 #include "install/install.h"
@@ -524,7 +523,6 @@
 Device::BuiltinAction start_recovery(Device* device, const std::vector<std::string>& args) {
   static constexpr struct option OPTIONS[] = {
     { "fastboot", no_argument, nullptr, 0 },
-    { "fsck_unshare_blocks", no_argument, nullptr, 0 },
     { "install_with_fuse", no_argument, nullptr, 0 },
     { "just_exit", no_argument, nullptr, 'x' },
     { "locale", required_argument, nullptr, 0 },
@@ -557,7 +555,6 @@
   bool rescue = false;
   bool just_exit = false;
   bool shutdown_after = false;
-  bool fsck_unshare_blocks = false;
   int retry_count = 0;
   bool security_update = false;
   std::string locale;
@@ -580,9 +577,7 @@
         break;
       case 0: {
         std::string option = OPTIONS[option_index].name;
-        if (option == "fsck_unshare_blocks") {
-          fsck_unshare_blocks = true;
-        } else if (option == "install_with_fuse") {
+        if (option == "install_with_fuse") {
           install_with_fuse = true;
         } else if (option == "locale" || option == "fastboot" || option == "reason") {
           // Handled in recovery_main.cpp
@@ -779,10 +774,6 @@
     save_current_log = true;
     status = ApplyFromAdb(device, true /* rescue_mode */, &next_action);
     ui->Print("\nInstall from ADB complete (status: %d).\n", status);
-  } else if (fsck_unshare_blocks) {
-    if (!do_fsck_unshare_blocks()) {
-      status = INSTALL_ERROR;
-    }
   } else if (!just_exit) {
     // If this is an eng or userdebug build, automatically turn on the text display if no command
     // is specified. Note that this should be called before setting the background to avoid