test/test_metaflac.sh: POSIXify embedded awk script.

The embedded awk script was using the 'lshift' function which
apparently only exists in GNU auk (gawk) and definitely does not
exist in mawk.

Thanks to Martijn van Beurden <mvanb1@gmail.com> for reporting
this issue.

diff --git a/test/test_metaflac.sh b/test/test_metaflac.sh
index 113e19f..9a13291 100755 (executable)
--- a/test/test_metaflac.sh
+++ b/test/test_metaflac.sh
@@ -399,6 +399,7 @@ echo OK
 
 tonegenerator ()
 {
+       # When using GAWK, use --lint=posix to identify non-POSIX awk usages.
     awk -- '
     BEGIN {
             samplerate = '$1';
@@ -407,7 +408,11 @@ tonegenerator ()
             duration = 1;
             bitspersample = 24;
 
-            samplemidpoint = lshift(1, (bitspersample-1));
+            samplemidpoint = 1;
+                       for (sps = 0 ; sps < bitspersample - 1 ; sps++) {
+                               samplemidpoint *= 2;
+                       }
+
             samplerange = samplemidpoint - 1;
 
             pi = 4 * atan2(1,1);