installer: allow disabling Git LFS

If the checkbox is unchecked, we will simply delete `git-lfs.exe` and
remove the corresponding section in the system-wide config.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

installer/install.iss

@@ -95,6 +95,7 @@ Name: icons\desktop; Description: On the Desktop
 Name: ext; Description: Windows Explorer integration; Types: default
 Name: ext\shellhere; Description: Git Bash Here; Types: default
 Name: ext\guihere; Description: Git GUI Here; Types: default
+Name: gitlfs; Description: Git LFS (Large File Support); Types: default; Flags: disablenouninstallwarning
 Name: assoc; Description: Associate .git* configuration files with the default text editor; Types: default
 Name: assoc_sh; Description: Associate .sh files to be run with Bash; Types: default
 Name: consolefont; Description: Use a TrueType font in all console windows
@@ -2045,6 +2046,17 @@ begin
             LogError('Line {#__LINE__}: Unable to create "Git GUI Here" shell extension.');
     end;
 
+    {
+        Optionally disable Git LFS completely
+    }
+
+    if not IsComponentSelected('gitlfs') then begin
+        if not Exec(AppDir + '\{#MINGW_BITNESS}\bin\git.exe','config --system --remove-section filter.lfs','',SW_HIDE,ewWaitUntilTerminated, i) then
+            LogError('Could not disable Git LFS in the gitconfig.');
+        if not DeleteFile(AppDir+'\{#MINGW_BITNESS}\libexec\git-core\git-lfs.exe') and not DeleteFile(AppDir+'\{#MINGW_BITNESS}\bin\git-lfs.exe') then
+            LogError('Line {#__LINE__}: Unable to delete "git-lfs.exe".');
+    end;
+
     {
         Run post-install scripts to set up system environment
     }