Use autoconf variable for C preprocessor

This fixes the build when cross-compiling, where the preprocessor might
be prefixed.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Ben Wolsieffer <benwolsieffer@gmail.com>
Closes #8180

diff --git a/config/kernel.m4 b/config/kernel.m4
index 118f1d8dc5b0c7a27969c02307e21ee296e051b5..7330c00e1bd20555cbfd60bba31102afca25e1ad 100644 (file)
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -275,7 +275,7 @@ AC_DEFUN([ZFS_AC_KERNEL], [
        AS_IF([test "$utsrelease"], [
                kernsrcver=`(echo "#include <$utsrelease>";
                             echo "kernsrcver=UTS_RELEASE") |
-                            cpp -I $kernelbuild/include |
+                            ${CPP} -I $kernelbuild/include - |
                             grep "^kernsrcver=" | cut -d \" -f 2`
 
                AS_IF([test -z "$kernsrcver"], [