remove the autoconf+Make buildsystem

We're not using it anymore. Any leftover bugs in the Meson buildsystem
are now just bugs.

Closes #249.

Change-Id: I0465a0c37ae819f94d40e7829f5bff046aa63d73

tests/unit/libexpr/local.mk

@@ -1,32 +0,0 @@
-check: libexpr-tests_RUN
-
-programs += libexpr-tests
-
-libexpr-tests_NAME := libnixexpr-tests
-
-libexpr-tests_ENV := _NIX_TEST_UNIT_DATA=$(d)/data
-
-libexpr-tests_DIR := $(d)
-
-libexpr-tests_INSTALL_DIR :=
-
-libexpr-tests_SOURCES := \
-    $(wildcard $(d)/*.cc) \
-    $(wildcard $(d)/value/*.cc)
-
-libexpr-tests_EXTRA_INCLUDES = \
-    -I tests/unit/libexpr-support \
-    -I tests/unit/libstore-support \
-    -I tests/unit/libutil-support \
-    -I src/libexpr \
-    -I src/libfetchers \
-    -I src/libstore \
-    -I src/libutil
-
-libexpr-tests_CXXFLAGS += $(libexpr-tests_EXTRA_INCLUDES)
-
-libexpr-tests_LIBS = \
-    libexpr-test-support libstore-test-support libutils-test-support \
-    libexpr libfetchers libstore libutil
-
-libexpr-tests_LDFLAGS := -lrapidcheck $(GTEST_LIBS) -lgmock