Merge bitcoin/bitcoin#23658: contrib: add check for wget command in install_db4.sh

b062da0090 contrib: add check for wget command in install_db4.sh (Florian Baumgartl)

Pull request description:

  This PR is motivated by 7bb8eb0bc3 commit (see also https://github.com/bitcoin/bitcoin/pull/23579) and ensures that `install_db4.sh` will check for `curl` and `wget` utilities. Currently, the conditional statement in the `http_get()` function assumes that `wget` is always available but we actually do not know it since there is no check or validation for the `wget` command. So let's make sure that we check for both commands and print an error message if they are missing.

ACKs for top commit:
  jamesob:
    ACK b062da0090
  laanwj:
    Tested ACK b062da0090
  shaavan:
    ACK b062da0090

Tree-SHA512: bfc1ccad9a5b99764b759e02dde1976616c2af4747b7d5af8e71d33624c2cb21d93a09a60d244756e86bbd5fd7541331c62d7eb84d3458b6a059f1d9cb2a5f42

contrib/install_db4.sh

@@ -55,8 +55,11 @@ http_get() {
     echo "File ${2} already exists; not downloading again"
   elif check_exists curl; then
     curl --insecure --retry 5 "${1}" -o "${2}"
-  else
+  elif check_exists wget; then
     wget --no-check-certificate "${1}" -O "${2}"
+  else
+    echo "Simple transfer utilities 'curl' and 'wget' not found. Please install one of them and try again."
+    exit 1
   fi
 
   sha256_check "${3}" "${2}"
@@ -64,7 +67,7 @@ http_get() {
 
 # Ensure the commands we use exist on the system
 if ! check_exists patch; then
-    echo "Command-line tool 'patch' not found.  Install patch and try again."
+    echo "Command-line tool 'patch' not found. Install patch and try again."
     exit 1
 fi