[AArch64] Skip test aarch64-init-cpu-features if FMV runtime unavailable. (#269)

The test aarch64-init-cpu-features is conditionally built depending on
whether the FMV runtime is available. When the test-suite is built using
CMake it is handled here: #172

This patch fixes build errors when running LNT tests on AArch64 using
Make rather than CMake:
* It selects between __init_cpu_features_resolver and __init_cpu_features.
* Attempts to compile a dummy program using TARGET_LLVMGCC
   to detect availability of the selected symbol.
* Adds corresponding macro (HAS_DARWIN_FMV or HAS_LINUX_FMV)
   if detection succeeds.
* Skips test if the symbol is undefined.

Co-authored-by: Alexandros Lamprineas alexandros.lamprineas@arm.com
Co-authored-by: Momchil Velikov momchil.velikov@arm.com

Author: IamYJLee

SingleSource/Benchmarks/Misc/Makefile

@@ -12,6 +12,29 @@ PROGRAMS_TO_SKIP := dt
 endif
 endif
 
+ifeq ($(ARCH),AArch64)
+ifeq ($(TARGET_OS),Darwin)
+SYMBOL = __init_cpu_features_resolver
+endif
+ifeq ($(TARGET_OS),Linux)
+SYMBOL = __init_cpu_features
+endif
+# TARGET_LLVMGCC refers to the compiler specified with the --cc option,
+# and can be checked in the build-tools.log file in the test results directory.
+SYMBOL := $(shell echo "extern void $(SYMBOL)(void); void (*p)() = $(SYMBOL); int main() {}" | \
+       $(TARGET_LLVMGCC) --rtlib=compiler-rt -x c - -o /dev/null 2>/dev/null && \
+       echo $(SYMBOL) || echo undefined)
+ifeq ($(SYMBOL),__init_cpu_features_resolver)
+CFLAGS += --rtlib=compiler-rt -DHAS_DARWIN_FMV
+endif
+ifeq ($(SYMBOL),__init_cpu_features)
+CFLAGS += --rtlib=compiler-rt -DHAS_LINUX_FMV
+endif
+ifeq ($(SYMBOL),undefined)
+PROGRAMS_TO_SKIP := aarch64-init-cpu-features
+endif
+endif
+
 ifeq ($(ARCH),Mips)
 RUNTIMELIMIT := 2000
 endif