Because file names are not enclosed in quotation marks in the open call.
https://bugs.chromium.org/p/boringssl/issues/detail?id=415
```
cmake --build "C:\Projects\ Extern\Visual C++ 2015\x64 Debug\Build\BoringSSL\."
[9/439] Generating rdrand-x86_64.asm
FAILED: crypto/fipsmodule/rdrand-x86_64.asm
cmd.exe /C "cd /D "C:\Projects\ Extern\Visual C++ 2015\x64 Debug\Build\BoringSSL\crypto\fipsmodule" && "C:\Program Files\CMake\bin\cmake.exe" -E make_directory . && C:\Perl64\bin\perl.exe "C:/Projects/ Extern/Source/BoringSSL/crypto/fipsmodule/rand/asm/rdrand-x86_64.pl" nasm rdrand-x86_64.asm"
Can't open perl script "C:/Projects/": No such file or directory
error closing STDOUT at C:/Projects/ Extern/Source/BoringSSL/crypto/fipsmodule/rand/asm/rdrand-x86_64.pl line 87.
ninja: build stopped: subcommand failed.
```
Bug: 415
Change-Id: I83c4a460689b9adeb439425ad390322ae8b2002a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47884
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
7a3e801217