Don't warn about overlength strings in test data

Signed-off-by: Laslo Hunhold <dev@frign.de>

config.mk

diff --git a/config.mk b/config.mk
index c5284c5..f477480 100644
--- a/config.mk
+++ b/config.mk
@@ -15,7 +15,7 @@
 
 # flags
 CPPFLAGS = -D_ISOC99_SOURCE
-CFLAGS   = -std=c99 -Os -Wall -Wextra -Wpedantic
+CFLAGS   = -std=c99 -Os -Wall -Wextra -Wpedantic -Wno-overlength-strings
 LDFLAGS  = -s
 
 BUILD_CPPFLAGS = $(CPPFLAGS)