apply: avoid fixed-size buffer in create_one_file()

PATH_MAX is not always a hard limit and 'path' in create_one_file() could be longer -- it's taken from the patch file and allocated dynamically. Allocate the name of the temporary file on the heap as well instead of using a fixed-size buffer to avoid that arbitrary limit. Resist the temptation of using the more convenient mkpath() to avoid introducing a dependency on a static variable deep inside the apply machinery. Take care to work around (arguably buggy) implementations of free(3) that modify errno, by calling it only after using the errno value. Suggested-by: Jeff King <peff@peff.net> Helped-by: Jeff King <peff@peff.net> Signed-off-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>