package/libsvgtiny: disable parallel build

Build can sometimes fails on:

src/svgtiny.c:21:10: fatal error: autogenerated_colors.c: No such file or directory
 #include "autogenerated_colors.c"
          ^~~~~~~~~~~~~~~~~~~~~~~~

because svgtiny.c does not properly depends on autogenerated_colors.c
that is built by gperf. So, just disable parallel build instead of
trying to fix this issue especially because libsvgtiny uses the netsurf
buildsystem

Fixes:
 - http://autobuild.buildroot.org/results/48e7a7f7c72634d59cca817778d31661bfe8e72f

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 26d67a2599d6c88facd5178de853fa355244e7c2)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libsvgtiny/libsvgtiny.mk

@@ -12,6 +12,8 @@ LIBSVGTINY_DEPENDENCIES = \
 	libxml2 host-gperf host-pkgconf host-netsurf-buildsystem
 LIBSVGTINY_LICENSE = MIT
 LIBSVGTINY_LICENSE_FILES = README
+# Package does not build in parallel due to improper make rules
+LIBSVGTINY_MAKE = $(MAKE1)
 
 # The libsvgtiny build system cannot build both the shared and static
 # libraries. So when the Buildroot configuration requests to build