Merge bitcoin#30986: contrib: skip missing binaries in gen-manpages

ee61853 gen-manpages: Prompt error if no binaries are found (Andre)
299e222 gen-manpages: implement --skip-missing-binaries (Andre Alves)

Pull request description:

  Instead of stopping the execution of gen-manpages.py when a binary is not found, continue generating manpages for the available binaries and skip the missing ones.

  A new argument, `--skip-missing-binaries`, has been added to enable this behavior.

  ```sh
  ➜  bitcoin git:(fix-gen-manpages) ✗ ./contrib/devtools/gen-manpages.py --help
  usage: gen-manpages.py [-h] [-s]

  options:
    -h, --help            show this help message and exit
    -s, --skip-missing-binaries
                          skip generation for binaries that are not found

  ```

  closes bitcoin#30985

  This PR also includes an error prompt if no binaries are found in the build path.

ACKs for top commit:
  achow101:
    ACK ee61853
  laanwj:
    re-ACK ee61853

Tree-SHA512: af4a0a5e26e508a51ab63f8aa9f98a6d6af9d7682a16791d8a6a61d49e44cb0147453f628ad5910f65d4efa6e3c7b6605c007259c23230b54888845bfaeb050c

contrib/devtools/gen-manpages.py

@@ -6,6 +6,7 @@
 import subprocess
 import sys
 import tempfile
+import argparse
 
 BINARIES = [
 'src/bitcoind',
@@ -16,6 +17,18 @@
 'src/qt/bitcoin-qt',
 ]
 
+parser = argparse.ArgumentParser(
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+)
+parser.add_argument(
+    "-s",
+    "--skip-missing-binaries",
+    action="store_true",
+    default=False,
+    help="skip generation for binaries that are not found in the build path",
+)
+args = parser.parse_args()
+
 # Paths to external utilities.
 git = os.getenv('GIT', 'git')
 help2man = os.getenv('HELP2MAN', 'help2man')
@@ -38,8 +51,12 @@
     try:
         r = subprocess.run([abspath, "--version"], stdout=subprocess.PIPE, check=True, text=True)
     except IOError:
-        print(f'{abspath} not found or not an executable', file=sys.stderr)
-        sys.exit(1)
+        if(args.skip_missing_binaries):
+            print(f'{abspath} not found or not an executable. Skipping...', file=sys.stderr)
+            continue
+        else:
+            print(f'{abspath} not found or not an executable', file=sys.stderr)
+            sys.exit(1)
     # take first line (which must contain version)
     verstr = r.stdout.splitlines()[0]
     # last word of line is the actual version e.g. v22.99.0-5c6b3d5b3508
@@ -51,6 +68,10 @@
 
     versions.append((abspath, verstr, copyright))
 
+if not versions:
+    print(f'No binaries found in {builddir}. Please ensure the binaries are present in {builddir}, or set another build path using the BUILDDIR env variable.')
+    sys.exit(1)
+
 if any(verstr.endswith('-dirty') for (_, verstr, _) in versions):
     print("WARNING: Binaries were built from a dirty tree.")
     print('man pages generated from dirty binaries should NOT be committed.')