Don't compile examples that require CBLAS and LAPACK when packages are not available

configure.ac

@@ -143,6 +143,11 @@ AC_MSG_RESULT($rtc_ok)
 # Check for feenableexcept, should be present in C99, also checks for -lm.
 AC_CHECK_LIB([m],[feenableexcept])
 
+# Some examples require CBLAS and LAPACK, check for that and set conditional.
+AC_CHECK_HEADER([cblas.h])
+AC_CHECK_HEADER([lapacke.h])
+AM_CONDITIONAL([HAVECBLAS], [test $ac_cv_header_cblas_h = "yes" -a $ac_cv_header_lapacke_h = "yes"])
+
 # Check for git, needed for revision stamps.
 AC_PATH_PROG([GIT_CMD], [git])
 AC_SUBST([GIT_CMD])

examples/Makefile.am

@@ -22,7 +22,10 @@ AM_CFLAGS = -I../src -DCPU_TPS=2.67e9 -DTIMERS
 AM_LDFLAGS =
 
 # Set-up the library
-bin_PROGRAMS = test test_qr test_bh test_bh_sorted test_fmm_sorted
+bin_PROGRAMS = test test_bh test_bh_sorted test_fmm_sorted
+if HAVECBLAS
+bin_PROGRAMS += test_qr 
+endif
 
 # Sources for test
 test_SOURCES = test.c