build: merge everything to a single top-level Makefile

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>

src/link/.gitignore

@@ -1,2 +0,0 @@
-# executable
-xlink

src/link/Makefile

@@ -1,21 +0,0 @@
-obj := \
-	assign.o \
-	library.o \
-	main.o \
-	mapfile.o \
-	object.o \
-	output.o \
-	patch.o \
-	symbol.o
-
-all: xlink
-
-clean:
-	rm -rf xlink $(obj)
-
-xlink: $(obj)
-	gcc -Wall -o $@ $^
-
-.c.o:
-	gcc -Wall -I../../include -g -c -o $@ $<
-