[Buildroot] [git commit] package/mbedtls: fix build with gcc 4.8

[Thomas Petazzoni]

commit: https://git.buildroot.net/buildroot/commit/?id=ef4dfe8fcee9fff152d938619562776a9ae03c18
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/master

Fix the following build failure with gcc 4.8 raised since bump to
version 2.28.0 in commit 0f8aab08e762742d753d5920718f31c629d0f8d7:

/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/mbedtls-2.28.0/library/bignum.c: In function 'mpi_select':
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/mbedtls-2.28.0/library/bignum.c:1994:5: error: 'for' loop initial declarations are only allowed in C99 mode
     for( size_t i = 0; i < T_size; i++ )
     ^
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/mbedtls-2.28.0/library/bignum.c:1994:5: note: use option -std=c99 or -std=gnu99 to compile your code

Fixes:
 - http://autobuild.buildroot.org/results/56ac0a8726d09eed8f45f865934fa7781a0e667a

Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
---
 package/mbedtls/mbedtls.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/package/mbedtls/mbedtls.mk b/package/mbedtls/mbedtls.mk
index 5facb99b2a..8745ff33f4 100644
--- a/package/mbedtls/mbedtls.mk
+++ b/package/mbedtls/mbedtls.mk
@@ -7,6 +7,7 @@
 MBEDTLS_VERSION = 2.28.0
 MBEDTLS_SITE = $(call github,ARMmbed,mbedtls,v$(MBEDTLS_VERSION))
 MBEDTLS_CONF_OPTS = \
+	-DCMAKE_C_FLAGS="$(TARGET_CFLAGS) -std=c99" \
 	-DENABLE_PROGRAMS=$(if $(BR2_PACKAGE_MBEDTLS_PROGRAMS),ON,OFF) \
 	-DENABLE_TESTING=OFF \
 	-DMBEDTLS_FATAL_WARNINGS=OFF