Warnings observed, when libfyaml is built without autotools

[kanjoe24]

Warnings observed, when libfyaml is built without autotools as described in the description:

Steps to reproduce:

1. git clone https://github.com/pantoniou/libfyaml.git
2. cp inprogram.c into libfyaml/.
   //inprogram.c is received from https://github.com/pantoniou/libfyaml#libfyaml-example-using-simplified-inprogram-yaml-generation
3. Warnings are observed.

libfyaml (master)$ gcc -ggdb -O0 -Wall src/lib/*.c src/thread/*.c src/util/*.c src/xxhash/*.c inprogram.c -I./include/ -I./src/util/ -I./src/xxhash/ -I./src/lib/ -I./src/thread/
src/lib/fy-diag.c: In function ‘fy_diag_vprintf’:
src/lib/fy-diag.c:405:22: warning: implicit declaration of function ‘vasprintf’; did you mean ‘vsprintf’? [-Wimplicit-function-declaration]
  405 |                 rc = vasprintf(&buf, fmt, ap);
      |                      ^~~~~~~~~
      |                      vsprintf
src/lib/fy-doc.c: In function ‘fy_node_get_parent_address’:
src/lib/fy-doc.c:4816:23: warning: implicit declaration of function ‘asprintf’; did you mean ‘vsprintf’? [-Wimplicit-function-declaration]
 4816 |                 ret = asprintf(&path, "%d", idx);
      |                       ^~~~~~~~
      |                       vsprintf
src/lib/fy-event.c: In function ‘fy_emit_scalar_vprintf’:
src/lib/fy-event.c:593:14: warning: implicit declaration of function ‘vasprintf’; did you mean ‘vsprintf’? [-Wimplicit-function-declaration]
  593 |         rc = vasprintf(&buf, fmt, ap);
      |              ^~~~~~~~~
      |              vsprintf
src/lib/fy-input.c: In function ‘fy_input_create’:
src/lib/fy-input.c:1014:23: warning: implicit declaration of function ‘asprintf’; did you mean ‘vsprintf’? [-Wimplicit-function-declaration]
 1014 |                 ret = asprintf(&fyi->name, "<fd-%d>", fyic->fd.fd);
      |                       ^~~~~~~~
      |                       vsprintf
src/lib/fy-parse.c: In function ‘fy_library_version’:
src/lib/fy-parse.c:40:2: warning: #warning No version defined [-Wcpp]
   40 | #warning No version defined
      |  ^~~~~~~
src/lib/fy-token.c: In function ‘fy_token_debug_text’:
src/lib/fy-token.c:1549:14: warning: implicit declaration of function ‘asprintf’; did you mean ‘vsprintf’? [-Wimplicit-function-declaration]
 1549 |         rc = asprintf(&buf, "%s:%.*s%s", typetxt, wlen, text, wlen < (int)length ? "..." : "");
      |              ^~~~~~~~
      |              vsprintf
src/lib/fy-walk.c: In function ‘fy_walk_result_vdump’:
src/lib/fy-walk.c:68:22: warning: implicit declaration of function ‘vasprintf’; did you mean ‘vsprintf’? [-Wimplicit-function-declaration]
   68 |                 rc = vasprintf(&banner, fmt, ap);
      |                      ^~~~~~~~~
      |                      vsprintf
src/lib/fy-walk.c: In function ‘fy_scalar_walk_result_to_expr’:
src/lib/fy-walk.c:4371:22: warning: implicit declaration of function ‘asprintf’; did you mean ‘vsprintf’? [-Wimplicit-function-declaration]
 4371 |                 rc = asprintf(&buf, "%d", (int)fwr->number);
      |                      ^~~~~~~~
      |                      vsprintf
jpn323@janus ~/workspace/libfyaml/libfyaml (master)$ 
jpn323@janus ~/workspace/libfyaml/libfyaml (master)$ 
jpn323@janus ~/workspace/libfyaml/libfyaml (master)$ ./a.out 
# invoice number was 34843
# given name is Chris
bill-to: &id001
  address:
    lines: |
      458 Walkman Dr.
      Suite #292
  delivery-address:
    lines: |
      1226 Windward Ave.
  family: Dumars
  given: Chris
  spouse: Doris
date: !!str 2001-01-23
invoice: 34844