MDEV-6039 - WebScaleSQL patches

Use single quotes for perl paths, in case of special symbols

Double-quoted string literals are subject to backslash and variable
substitution.

mysql-test/mtr.out-of-source

 #!/usr/bin/perl
 # Call mtr in out-of-source build
-$ENV{MTR_BINDIR} = "@CMAKE_BINARY_DIR@";
-chdir("@CMAKE_SOURCE_DIR@/mysql-test");
-exit(system($^X, "@CMAKE_SOURCE_DIR@/mysql-test/mysql-test-run.pl", @ARGV) >> 8);
+$ENV{MTR_BINDIR} = '@CMAKE_BINARY_DIR@';
+chdir('@CMAKE_SOURCE_DIR@/mysql-test');
+exit(system($^X, '@CMAKE_SOURCE_DIR@/mysql-test/mysql-test-run.pl', @ARGV) >> 8);
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