Buffer writing of crash dumps

Writing of crash dumps were done using unbuffered IO. This
is slow since many small writes are done.

Use a FILE* with an allocated buffer to obtain buffered IO.

I wrote a small test program that created 50000 binaries of 200 bytes
each and then created a crash dump. The crash dumping was an order of
magnitude faster with buffered IO than without.

1 files changed, 1 insertions, 0 deletions

diff --git a/erts/include/internal/erl_printf.h b/erts/include/internal/erl_printf.h
index f180a53f18..7e9807f6a8 100644
--- a/erts/include/internal/erl_printf.h
+++ b/erts/include/internal/erl_printf.h
@@ -44,6 +44,7 @@ struct erts_dsprintf_buf_t_ {
 typedef int (*fmtfn_t)(void*, char*, size_t);
 
 int erts_write_fd(void *vfdp, char* buf, size_t len);
+int erts_write_fp(void *vfdp, char* buf, size_t len);
 int erts_write_ds(void *vdsbufp, char* buf, size_t len);
 
 int erts_printf(const char *, ...);