Someone has uploaded a PDF to github, here:

https://github.com/VernonGrant/gnu-c-language-manual

I am stupid, too. I generally do not use git(1). I wrote a short script to download the manual as a single 639K text file. I do not use a GUI or mouse so this makes it easier for me to work with code snippets. I also reformat the text to match personal preferences. Here is an example script using popular curl program to make the HTTP requests.

    # requirements: curl, links, perl, texinfo (Linux), texi2html (BSD)

    #!/bin/sh
    set -v;
    x0=c-intro-and-ref.git;
    x1=https://git.savannah.nongnu.org/cgit/;
    test -d $x0||mkdir $x0;cd $x0||exit;
    for x2 in Makefile c.texi cpp.texi fdl.texi fp.texi texinfo.tex;do
    echo url=$x1$x0/plain/$x2;
    echo output=$x2;
    echo user-agent=\"\";
    done|curl -K/dev/stdin -s;
    case $(uname) in :)
    ;;*BSD) texi2html --no-headers --no-split --html c.texi
    ;;Linux) makeinfo --no-headers --no-split --html c.texi
    esac;
    # personal preference for ~15-inch screen: 4 space indent, 60-70 max chars per line
    links -width 70 -dump .html \
    |sed '/^ *Link:/d;/^ *\*/s/\*//;s/^/    /;/Jump to: /{N;N;d;}' > c.txt;
    exec less c.txt;

There's no direct PDF, you have to build it yourself w/ TeX by cloning the repo:

  git clone https://git.savannah.gnu.org/git/c-intro-and-ref.git
  cd c-intro-and-ref/
  make c.pdf

There is no pdf. Following the chain, you get to a git you can download. But this guy has a tar of it as a single html page.

https://forums.linuxmint.com/viewtopic.php?t=381284

There is no PDF.