Use printf %s rather than echo -n, for portability

Signed-off-by: Kerin Millar <kfm@plushkava.net>
Closes: https://bugs.gentoo.org/687382

--- a/configure	2000-07-29 18:00:28.000000000 +0000
+++ b/configure	2021-01-07 15:14:41.723651734 +0000
@@ -87,7 +87,7 @@
 EOF
 
 if [ x"$CC" = x ]; then
-    echo -n 'Looking for a C compiler... '
+    printf %s 'Looking for a C compiler... '
     for TRY in egcs gcc g++ CC c++ cc; do
        (
            $TRY __conftest.c -o __conftest || exit 1;
@@ -104,7 +104,7 @@
     fi
     echo "$CC"
 else
-    echo -n 'Checking if C compiler works... '
+    printf %s 'Checking if C compiler works... '
     if (
           $CC __conftest.c -o __conftest || exit 1
           ./__conftest || exit 1
@@ -118,7 +118,7 @@
      fi
 fi
 
-echo -n "Checking if $CC accepts gcc warnings... "
+printf %s "Checking if $CC accepts gcc warnings... "
 if (
     $CC $WARNINGS __conftest.c -o __conftest || exit 1
    ) >/dev/null 2>&1; then
@@ -129,7 +129,7 @@
 fi
 
 if [ x$DEBUG = x ]; then
-    echo -n "Checking if $CC accepts -O2... "
+    printf %s "Checking if $CC accepts -O2... "
     if (
          $CC -O2 __conftest.c -o __conftest
        ) >/dev/null 2>&1; then
@@ -137,7 +137,7 @@
          CFLAGS="$CFLAGS -O2"
     else
          echo 'no'
-         echo -n "Checking if $CC accepts -O... "
+         printf %s "Checking if $CC accepts -O... "
          if (
               $CC -O __conftest.c -o __conftest
             ) >/dev/null 2>&1; then
@@ -149,7 +149,7 @@
     fi
 
 else
-    echo -n "Checking if $CC accepts -g... "
+    printf %s "Checking if $CC accepts -g... "
     if (
          $CC -g __conftest.c -o __conftest
        ) >/dev/null 2>&1; then
@@ -168,7 +168,7 @@
 
 ##################################################
 
-echo -n 'Checking for BSD signal semantics... '
+printf %s 'Checking for BSD signal semantics... '
 cat <<EOF >__conftest.c
 #include <unistd.h>
 #include <signal.h>
@@ -208,7 +208,7 @@
 
 ##################################################
 
-echo -n 'Checking for socklen_t... '
+printf %s 'Checking for socklen_t... '
 cat <<EOF >__conftest.c
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -249,7 +249,7 @@
 
 ##################################################
 
-echo -n 'Checking for snprintf declaration... '
+printf %s 'Checking for snprintf declaration... '
 cat <<EOF >__conftest.c
 #include <stdio.h>
 int main() {
@@ -277,7 +277,7 @@
 fi
 rm -f __conftest*
 
-echo -n 'Checking for snprintf implementation... '
+printf %s 'Checking for snprintf implementation... '
 cat <<EOF >__conftest.c
 #include <stdio.h>
 #include <string.h>
@@ -333,7 +333,7 @@
 
 echo 'Generating MCONFIG...'
 (
-    echo -n '# Generated by configure (confgen version 2) on '
+    printf %s '# Generated by configure (confgen version 2) on '
     date
     echo '#'
     echo