Only try to parse git hash if .git is present

Closes 2451

build.bat

@@ -48,8 +48,11 @@ set odin_version_raw="dev-%curr_year%-%curr_month%"
 set compiler_flags= -nologo -Oi -TP -fp:precise -Gm- -MP -FC -EHsc- -GR- -GF
 set compiler_defines= -DODIN_VERSION_RAW=\"%odin_version_raw%\"
 
+if not exist .git\ goto skip_git_hash
 for /f %%i in ('git rev-parse --short HEAD') do set GIT_SHA=%%i
 if %ERRORLEVEL% equ 0 set compiler_defines=%compiler_defines% -DGIT_SHA=\"%GIT_SHA%\"
+:skip_git_hash
+
 if %nightly% equ 1 set compiler_defines=%compiler_defines% -DNIGHTLY
 
 if %release_mode% EQU 0 ( rem Debug