portable/installer: work around 32-bit issue with Windows 10

At least on one machine this developer has access to, the default base
address of the 32-bit `msys-2.0.dll` is no good on Windows 10, so we need
to adjust it.

It would be best, of course, if the Batch script could run any program to
guess the best base address, or whether it needs to be adjusted to begin
with, but so far none was identified.

Therefore, let's just stay with the hard-coded base address adjustment
when running in 32-bit mode on Windows 10, until a brilliant idea comes
along to make it better.

This fixes git-for-windows/git#361

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

installer/install.iss.in

@@ -188,6 +188,15 @@ Type: files; Name: {app}\Git Bash.lnk
 Type: dirifempty; Name: {app}\home\{username}
 Type: dirifempty; Name: {app}\home
 
+#ifdef IS32
+; Delete the files required for rebaseall
+Type: files; Name: {app}\bin\msys-2.0.dll
+Type: files; Name: {app}\bin\rebase.exe
+Type: dirifempty; Name: {app}\bin
+Type: files; Name: {app}\etc\rebase.db.i386
+Type: dirifempty; Name: {app}\etc
+#endif
+
 [Code]
 #include "helpers.inc.iss"
 #include "environment.inc.iss"

post-install.bat

@@ -15,6 +15,25 @@
 @REM We cannot use %PROCESSOR_ARCHITECTURE% for this test because it is
 @REM allowed to install a 32-bit Git for Windows into a 64-bit system.
 @IF EXIST mingw32\bin\git.exe @(
+	@REM We need to rebase just to make sure that it still works even with
+	@REM 32-bit Windows 10
+	@FOR /F "tokens=4 delims=.[XP " %%i IN ('ver') DO @SET ver=%%i
+	@IF 10 LEQ %ver @(
+		@REM We copy `rebase.exe` because it links to `msys-2.0.dll`
+		@REM (and @REM thus prevents modifying it). It is okay to
+		@REM execute `rebase.exe`, though, because the DLL base address
+		@REM problems only really show when other processes are
+		@REM `fork()`ed and `rebase.exe` does no such thing.
+		@IF NOT EXIST bin\rebase.exe @(
+			@IF NOT EXIST bin @MKDIR bin
+			@COPY usr\bin\rebase.exe bin\rebase.exe
+		)
+		@IF NOT EXIST bin\msys-2.0.dll @(
+			@COPY usr\bin\msys-2.0.dll bin\msys-2.0.dll
+		)
+		@bin\rebase.exe -b 0x64000000 usr\bin\msys-2.0.dll
+	)
+
 	usr\bin\dash.exe -c '/usr/bin/dash usr/bin/rebaseall -p'
 )