package/bcc: bump version to 0.31.0

For a change log since 0.29.1, see:
https://github.com/iovisor/bcc/blob/v0.31.0/debian/changelog

This commit also changes BCC_SITE_METHOD to "git". This is because the
upstream source archive name does not contain the version. It is
always named "bcc-src-with-submodule.tar.gz" in all releases. If using
the https _SITE_METHOD, bumping the version will not download the new
version if the directory BR2_DL_DIR contains an old one, with the same
name. Since the upstream repository uses git submodules, this commit
also adds "BCC_GIT_SUBMODULES = YES".

Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/bcc/bcc.hash

@@ -1,3 +1,3 @@
 # locally calculated
-sha256  321575fa94f3274040379dd2d4535217f45099f4240b58a4dfc171aa8c78402f  bcc-src-with-submodule.tar.gz
+sha256  5641b1db0b9ec60a6afd67b4607c790f49e580c207638bb4ebcea2805c6f373b  bcc-v0.31.0-git4.tar.gz
 sha256  b40930bbcf80744c86c46a12bc9da056641d722716c378f5659b9e555ef833e1  LICENSE.txt

package/bcc/bcc.mk

@@ -4,9 +4,10 @@
 #
 ################################################################################
 
-BCC_VERSION = 0.29.1
-BCC_SITE = https://github.com/iovisor/bcc/releases/download/v$(BCC_VERSION)
-BCC_SOURCE = bcc-src-with-submodule.tar.gz
+BCC_VERSION = v0.31.0
+BCC_SITE = https://github.com/iovisor/bcc
+BCC_SITE_METHOD = git
+BCC_GIT_SUBMODULES = YES
 BCC_LICENSE = Apache-2.0
 BCC_LICENSE_FILES = LICENSE.txt
 BCC_INSTALL_STAGING = YES