Also use the local cmake binary if available (for trusty) and take in account the PRE_PROCESS_CONF option

debian/changelog

@@ -6,6 +6,8 @@ llvm-toolchain-7 (1:7~+rc1-1~exp3) experimental; urgency=medium
   * Fixed "weak-library-dev-dependency libc++-7-dev on libc++-7-helpers"
   * Fixed "libomp5-7: shlibs-declares-dependency-on-other-package
            libomp5-7) (>= 1:7~svn298832-1~)"
+  * Also use the local cmake binary if available (for trusty)
+    and take in account the PRE_PROCESS_CONF option
 
   [ Reshabh Sharma ]
   * Fixed "Lintian warnings for libc++abi-7-dev package"

debian/rules

@@ -354,8 +354,13 @@ endif
 	mkdir -p libcxxabi/build
 	mkdir -p libcxx/build
 
+	CMAKE_BIN=cmake; \
+	if test -f /tmp/cmake/bin/cmake; then \
+		CMAKE_BIN=/tmp/cmake/bin/cmake; \
+	fi; \
+	echo "Using cmake: $$CMAKE_BIN"; \
 	cd libcxxabi/build && \
-	cmake ../ \
+	$(PRE_PROCESS_CONF) $$CMAKE_BIN ../ \
 	$(LIBCXX_CMAKE_OPTIONS) \
 	-DLIBCXXABI_LIBCXX_PATH=$(BASE_PATH)/libcxx \
 	-DLIBCXXABI_LIBCXX_LIBRARY_PATH=$(BASE_PATH)/libcxx/build/lib \
@@ -364,8 +369,13 @@ endif
 	-DLLVM_ENABLE_RTTI=ON && \
 	$(MAKE) $(NJOBS) VERBOSE=1
 
+	CMAKE_BIN=cmake; \
+	if test -f /tmp/cmake/bin/cmake; then \
+		CMAKE_BIN=/tmp/cmake/bin/cmake; \
+	fi; \
+	echo "Using cmake: $$CMAKE_BIN"; \
 	cd libcxx/build && \
-	cmake ../ \
+	$(PRE_PROCESS_CONF) $$CMAKE_BIN ../ \
 	$(LIBCXX_CMAKE_OPTIONS) \
 	-DLIBCXX_CXX_ABI=libcxxabi \
 	-DLIBCXX_CXX_ABI_INCLUDE_PATHS=$(BASE_PATH)/libcxxabi/include \