Make failing stat() calls abort the build.
Fixes #830, fixes #904.
In practice, this either happens with 64-bit inodes and a 32-bit
userspace when building without -D_FILE_OFFSET_BITS=64 in CFLAGS, or
when a filename is longer than the system file length limit.
Since DiskInterface::Stat() returns -1 on error, and Node used -1 on
"stat state unknown", not aborting the build lead to ninja stat()ing the
same file over and over again, until it finally ran out of stack. That's
now fixed.
* Change RecomputeOutputsDirty() to return success instead of dirty
state (like RecomputeDirty()) and return the dirty state in a bool
outparam
* Node::Stat()s old return value wasn't used anywhere, change the
function to return success instead and add an |err| outparam
* Node::StatIfNecessary()'s old return value was used only in one place.
Change that place to explicitly check status_known() and make
StatIfNecessary() return success and add an |err| outparam
* Plan::CleanNode() can now fail, make it return bool and add an |err|
outparam