build/prereq: merge ifndef IB block together

Multiple prereq checks are only required within the build system but not
for the ImageBuilder. These checks are excluded by using ifndef IB.

This commit merges the three ifndef IB blocks together.

Signed-off-by: Paul Spooren <[email protected]>

include/prereq-build.mk

@@ -38,9 +38,7 @@ $(eval $(call TestHostCommand,working-gcc, \
 	it appears to be broken, \
 	echo 'int main(int argc, char **argv) { return 0; }' | \
 		gcc -x c -o $(TMP_DIR)/a.out -))
-endif
 
-ifndef IB
 $(eval $(call SetupHostCommand,g++, \
 	Please install the GNU C++ Compiler (g++) 4.8 or later, \
 	$(CXX) -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?|10\.?)', \
@@ -53,14 +51,12 @@ $(eval $(call TestHostCommand,working-g++, \
 	echo 'int main(int argc, char **argv) { return 0; }' | \
 		g++ -x c++ -o $(TMP_DIR)/a.out - -lstdc++ && \
 		$(TMP_DIR)/a.out))
-endif
 
-ifndef IB
 $(eval $(call TestHostCommand,ncurses, \
 	Please install ncurses. (Missing libncurses.so or ncurses.h), \
 	echo 'int main(int argc, char **argv) { initscr(); return 0; }' | \
 		gcc -include ncurses.h -x c -o $(TMP_DIR)/a.out - -lncurses))
-endif
+endif # IB
 
 ifeq ($(HOST_OS),Linux)
   zlib_link_flags := -Wl,-Bstatic -lz -Wl,-Bdynamic