Remove always_hybrid spec

With always_hybrid also the lx_hybrid_x86 platform in
tool/create_builddir vanishes.

Fixes #1619

tool/builddir/build.mk

@@ -95,11 +95,8 @@ endif
 #
 # Tool chain version check
 #
-# If SPECS contains 'always_hybrid' we skip the check as the host tool chain is
-# used. Also, empty DST_DIRS is interpreted as a tool-chain agnostic target,
-# e.g., clean.
+# Empty DST_DIRS is interpreted as a tool-chain agnostic target, e.g., clean.
 #
-ifeq ($(filter always_hybrid,$(SPECS)),)
 ifneq ($(DST_DIRS),)
 REQUIRED_GCC_VERSION ?= 4.9.2
 GCC_VERSION := $(filter $(REQUIRED_GCC_VERSION) ,$(shell $(CUSTOM_CXX) --version))
@@ -107,7 +104,6 @@ ifneq ($(GCC_VERSION), $(REQUIRED_GCC_VERSION))
 $(error "$(CUSTOM_CXX) version $(REQUIRED_GCC_VERSION) is required")
 endif
 endif
-endif
 
 #
 # Default rule: build all directories specified as make arguments

tool/builddir/etc/build.conf.lx_hybrid_x86

@@ -1,8 +0,0 @@
-REPOSITORIES  = $(GENODE_DIR)/repos/base-linux
-
-##
-## Kernel-specific run tool configuration
-##
-
-RUN_OPT = --include boot_dir/linux \
-          --include power_on/linux --include log/linux