libgit2: new package

Signed-off-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
[Thomas:
 - Do not select BR2_PACKAGE_ZLIB, because zlib is an optional
   dependency.
 - Handle optional dependencies in a more usual way in libgit2.mk:
   group the addition in _DEPENDENCIES and in _CONF_OPTS for a given
   library together.
 - libgit2 can optionally use libssh2, not libssh.
 - Add the optional dependency on zlib.
 - Always pass USE_ICONV=ON, the detection works perfectly fine, with
   both a C library providing iconv support built-in, and with
   libiconv. If neither provides iconv, it gets disabled automatically
   as expected.
 - Add libiconv as an optional dependency.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libgit2/libgit2.mk

@@ -0,0 +1,54 @@
+################################################################################
+#
+# libgit2
+#
+################################################################################
+
+LIBGIT2_VERSION = v0.26.0
+LIBGIT2_SITE = $(call github,libgit2,libgit2,$(LIBGIT2_VERSION))
+LIBGIT2_LICENSE = GPL-2.0 with linking exception
+LIBGIT2_LICENSE_FILES = COPYING
+LIBGIT2_INSTALL_STAGING = YES
+
+LIBGIT2_CONF_OPTS = \
+	-DUSE_GSSAPI=OFF \
+	-DBUILD_CLAR=OFF \
+	-DUSE_ICONV=ON \
+	-DTHREADSAFE=$(if $(BR2_TOOLCHAIN_HAS_THREADS),ON,OFF)
+
+# If libiconv is available (for !locale toolchains), then we can use
+# it for iconv support. Note that USE_ICONV=ON is still correct even
+# without libiconv because (1) most toolchain have iconv support
+# without libiconv and (2) even if USE_ICONV=ON but iconv support is
+# not available, libgit2 simply avoids using iconv.
+ifeq ($(BR2_PACKAGE_LIBICONV),y)
+LIBGIT2_DEPENDENCIES += libiconv
+endif
+
+# No option to explicitly enable/disable zlib
+ifeq ($(BR2_PACKAGE_ZLIB),y)
+LIBGIT2_DEPENDENCIES += zlib
+endif
+
+ifeq ($(BR2_PACKAGE_LIBSSH2),y)
+LIBGIT2_DEPENDENCIES += libssh2
+LIBGIT2_CONF_OPTS += -DUSE_SSH=ON
+else
+LIBGIT2_CONF_OPTS += -DUSE_SSH=OFF
+endif
+
+ifeq ($(BR2_PACKAGE_OPENSSL),y)
+LIBGIT2_DEPENDENCIES += openssl
+LIBGIT2_CONF_OPTS += -DUSE_OPENSSL=ON
+else
+LIBGIT2_CONF_OPTS += -DUSE_OPENSSL=OFF
+endif
+
+ifeq ($(BR2_PACKAGE_LIBCURL),y)
+LIBGIT2_DEPENDENCIES += libcurl
+LIBGIT2_CONF_OPTS += -DCURL=ON
+else
+LIBGIT2_CONF_OPTS += -DCURL=OFF
+endif
+
+$(eval $(cmake-package))