boost should not blindly assume that MinGW installation is in c:\ directory

[anonymous]

instead it should search the directory in which main boost dir lies and then if not found should withdraw to defauld directory

so in file : boost\tools\build\v2\engine\build.bat

if EXIST "C:\MinGW\bin\gcc.exe" (
    set "BOOST_JAM_TOOLSET=mingw"
    set "BOOST_JAM_TOOLSET_ROOT=C:\MinGW\"
    goto :eof)
call :Clear_Error

</pre> }}}

should instead be:

if EXIST "..\MinGW\bin\gcc.exe" (
    set "BOOST_JAM_TOOLSET=mingw"
    set "BOOST_JAM_TOOLSET_ROOT=..\MinGW\"
    goto :eof)
call :Clear_Error

to catch that mingw installation which lies along with boost in the same parent directory. This is needed in case both of them are run from removable drive or there are different pairs of boost and mingw for testing.