use cmake everywhere for desktop build, fix build warnings

src/decn/proto/CMakeLists.txt

@@ -0,0 +1,9 @@
+
+add_executable(div div_mfp.cpp)
+target_link_libraries(div gmp)
+
+add_executable(ln ln_mfp.cpp)
+target_link_libraries(ln mpfr)
+
+add_executable(exp exp.cpp)
+target_link_libraries(exp mpfr)

src/decn/proto/Makefile

@@ -1,10 +0,0 @@
-all: div ln exp
-
-div: div_mfp.cpp
-	g++ -Wall div_mfp.cpp -o div -lgmp
-
-ln: ln_mfp.cpp
-	g++ -Wall ln_mfp.cpp -o ln -lmpfr
-
-exp: exp.cpp
-	g++ -Wall exp.cpp -o exp -lmpfr