racy build failure on drmemory

_From [zhao...@google.com](https://code.google.com/u/106321947286816917100/) on March 10, 2013 21:21:18_

It seems there are some racy on building drmemory.
The build may fail something due to the error below:

zhaoqin@ZHAOQIN0-W ~/Workspace/DrMemory/builds/build_x86_dbg.svn
$ ninja
[1/309] Building ASM object tests\CMakeFiles\registers.dir\registers_asm.asm.obj
[2/309] Building CXX object tests\app_suite\CMakeFiles\app_suite_tests.dir\ntalpc_tests_win.cpp.obj
[3/309] Building CXX object tests\app_suite\CMakeFiles\app_suite_tests.dir\ntgdi_tests_win.cpp.obj
[4/309] Building CXX object tests\app_suite\CMakeFiles\app_suite_tests.dir\ntuser_tests_win.cpp.obj
[5/309] Building CXX object tests\app_suite\CMakeFiles\app_suite_tests.dir\ole_tests_win.cpp.obj
[6/309] Building CXX object tests\app_suite\CMakeFiles\app_suite_tests.dir\os_version_win.cpp.obj
registers_asm.asm
cl : Command line warning D9002 : ignoring unknown option '/Zd'
cl : Command line warning D9024 : unrecognized source file type 'tests\CMakeFiles\registers.dir\registers_asm.asm.obj.s', object file assumed
cl : Command line warning D9027 : source file 'tests\CMakeFiles\registers.dir\registers_asm.asm.obj.s' ignored
cl : Command line warning D9021 : no action performed
[7/309] Linking C executable tests\registers.exe
FAILED: cmd.exe /c cd . && "C:\Program Files (x86)\CMake 2.8\bin\cmake.exe" -E vs_link_exe C:\PROGRA~2\MICROS~1.0\VC\bin\cl.exe /nologo /DWIN32 /D_WINDOWS /Zm1000 /D_DEBUG /MT /Zi /Ob0 /Od /W2 /WX /GS- /MP /Fetests\registers.exe /Fdtests\registers.pdb tests\CMakeFiles\registers.dir\registers.c.obj tests\CMakeFiles\registers.dir\registers_asm.asm.obj /link /implib:tests\registers.lib /version:1.5 /STACK:10000000 /machine:X86 /debug /INCREMENTAL:YES /subsystem:console kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd .
LINK : fatal error LNK1104: cannot open file 'tests\CMakeFiles\registers.dir\registers_asm.asm.obj'
LINK Pass 1 failed. with 2
ninja: build stopped: subcommand failed.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=1166_