get only the first word after code_block_start in get_lang

[0fflineuser]

Currently it gets all the text after the start of the code block without the spaces.
Now it only get the first word so it can work in orgmode when it is followed by :tangle.

#+BEGIN_SRC c :tangle helloworld.c
#include <stdio.h>

int main(){
printf("Hello, world!\n");
}
#+END_SRC

Results: Hello, world!

[jubnzv]

LGTM. Thank you!