build: make UHD a required default dependency

by default cmake will fail if UHD is not found. The advanced user
can disable this though with: cmake -DENABLE_UHD=False ..

Author: andrepuschmann

CMakeLists.txt

@@ -58,7 +58,7 @@ option(ENABLE_TSAN           "Enable clang thread sanitizer"            OFF)
 option(ENABLE_ASAN           "Enable clang address sanitizer"           OFF)
 option(ENABLE_GCOV           "Enable code coverage"                     OFF)
 option(ENABLE_UHD            "Enable UHD"                               ON)
-option(ENABLE_ZEROMQ         "Enable ZeroMQ"                            ON)
+option(ENABLE_ZEROMQ         "Enable ZeroMQ"                            OFF)
 option(ENABLE_FFTW           "Enable FFTW"                              ON)
 option(ENABLE_EXPORT         "Enable PIC and export libraries"          OFF)
 option(AUTO_DETECT_ISA       "Enable automatic ISA detection"           ON)
@@ -188,7 +188,7 @@ find_package(Threads REQUIRED)
 
 # UHD
 if (ENABLE_UHD)
-    find_package(UHD)
+    find_package(UHD REQUIRED)
     if (UHD_FOUND)
         include_directories(${UHD_INCLUDE_DIRS})
         link_directories(${UHD_LIBRARY_DIRS})