makefile: Support absolute paths for dmd

With gdc and ldc2, DC=/usr/bin/ldc2 or other paths are correctly handled. With
dmd, ldmd2, or gdmd, this is not the case because the makefile requires that DC
must be exactly dmd, or ldmd2, or gdmd, absolute paths or versioned
exes (dmd-2.111) not being supported.

Signed-off-by: Andrei Horodniceanu <a.horodniceanu@proton.me>

Author: the-horo

makefile

@@ -66,7 +66,7 @@ override DMD_TEST_FLAGS += -w
 
 DC_DEBUG_FLAGS := -g -Jbin
 
-ifeq ($(DC), $(filter $(DC), dmd ldmd2 gdmd))
+ifneq (,$(findstring dmd, $(DC)))
 	VERSIONS := $(DMD_VERSIONS)
 	DEBUG_VERSIONS := $(DMD_DEBUG_VERSIONS)
 	DC_FLAGS += $(DMD_FLAGS)