depends: More robust cmake invocation

Specify well-known env vars instead of using a workaround to split up CC
and CXX.

depends/funcs.mk

@@ -157,12 +157,12 @@ ifneq ($($(1)_ldflags),)
 $(1)_autoconf += LDFLAGS="$$($(1)_ldflags)"
 endif
 
-$(1)_cmake=cmake -DCMAKE_INSTALL_PREFIX=$($($(1)_type)_prefix)
+$(1)_cmake=env CC="$$($(1)_cc)" CXX="$$($(1)_cxx)" CFLAGS="$$($(1)_cflags)" CXXFLAGS="$$($(1)_cxxflags)" cmake -DCMAKE_INSTALL_PREFIX:PATH=$($($(1)_type)_prefix)
 ifneq ($($(1)_type),build)
 ifneq ($(host),$(build))
-$(1)_cmake += -DCMAKE_SYSTEM_NAME=$($(host_os)_cmake_system) -DCMAKE_SYSROOT=$(host_prefix)
-$(1)_cmake += -DCMAKE_C_COMPILER_TARGET=$(host) -DCMAKE_C_COMPILER=$(firstword $($($(1)_type)_CC)) -DCMAKE_C_FLAGS="$(wordlist 2,1000,$($($(1)_type)_CC))"
-$(1)_cmake += -DCMAKE_CXX_COMPILER_TARGET=$(host) -DCMAKE_CXX_COMPILER=$(firstword $($($(1)_type)_CXX)) -DCMAKE_CXX_FLAGS="$(wordlist 2,1000,$($($(1)_type)_CXX))"
+$(1)_cmake += -DCMAKE_SYSTEM_NAME=$($(host_os)_cmake_system)
+$(1)_cmake += -DCMAKE_C_COMPILER_TARGET=$(host)
+$(1)_cmake += -DCMAKE_CXX_COMPILER_TARGET=$(host)
 endif
 endif
 endef