nimble: strip comment section from binary

After the Zig 0.9.0 release, compiling with the current snapcraft Zig
adds 30 KB to the comment section, repeating the clang version many
times.

Before this commit:

    $ readelf -p .comment ./configlet

    String dump of section '.comment':
      [     0]  clang version 13.0.1 (git@github.com:ziglang/zig-bootstrap.git 74211dd7f7e7174a2027641dfcfdb3fc5df62f0c)
      [...] (repeat for 30 KB)
      [  7969]  clang version 13.0.1 (git@github.com:ziglang/zig-bootstrap.git 74211dd7f7e7174a2027641dfcfdb3fc5df62f0c)
      [  79d2]  Linker: LLD 13.0.1 (git@github.com:ziglang/zig-bootstrap.git 74211dd7f7e7174a2027641dfcfdb3fc5df62f0c)

Binary size profile before this commit:

       FILE SIZE        VM SIZE
    --------------  --------------
     75.2%   368Ki  64.5%   368Ki    .text
      0.0%       0  19.6%   111Ki    .bss
     18.2%  89.1Ki  15.6%  89.1Ki    .rodata
      6.2%  30.6Ki   0.0%       0    .comment
      0.2%     816   0.1%     824    .data
      0.1%     640   0.0%       0    [ELF Section Headers]
      0.1%     392   0.1%     392    [ELF Program Headers]
      0.0%      64   0.0%      64    [ELF Header]
      0.0%      63   0.0%       0    .shstrtab
      0.0%       8   0.0%       8    .got
      0.0%       8   0.0%       8    [LOAD #1 [R]]
      0.0%       4   0.0%       3    .fini
      0.0%       3   0.0%       3    .init
    100.0%   489Ki 100.0%   570Ki    TOTAL

Let's just strip the comment section.

configlet.nimble

@@ -63,4 +63,4 @@ when defined(linux):
   after build:
     if existsEnv("GITHUB_ACTIONS") and findExe("zigcc").len > 0:
       echo "stripping binary..."
-      exec "strip -s ./configlet"
+      exec "strip -s -R .comment ./configlet"