examples/embedding: Add -fno-common to the sample compiler flags.

This makes no difference when files are linked directly into a target
application, but on macOS additional steps are needed to index common
symbols in static libraries. See https://stackoverflow.com/a/26581710

By not creating any common symbols, this problem is bypassed.

This will also trigger linker errors if there are cases where the same
symbol is defined in the host application.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

examples/embedding/Makefile

@@ -12,7 +12,7 @@ PROG = embed
 CFLAGS += -I.
 CFLAGS += -I$(EMBED_DIR)
 CFLAGS += -I$(EMBED_DIR)/port
-CFLAGS += -Wall -Og
+CFLAGS += -Wall -Og -fno-common
 
 SRC += main.c
 SRC += $(wildcard $(EMBED_DIR)/*/*.c) $(wildcard $(EMBED_DIR)/*/*/*.c)