llvm lto mode fails to compile on alpine #1800
Description
The error during AFL++ build on Alpine:
clang -O3 -funroll-loops -fPIC -D_FORTIFY_SOURCE=1 -Wall -g -Wno-cast-qual -Wno-variadic-macros -Wno-pointer-sign -I ./include/ -I ./instrumentation/ -DAFL_PATH=\"/usr/local/lib/afl\" -DBIN_PATH=\"/usr/local/bin\" -DLLVM_BINDIR=\"/usr/lib/llvm15/bin\" -DVERSION=\"++4.08a\" -DLLVM_LIBDIR=\"/usr/lib/llvm15/lib\" -DLLVM_VERSION=\"15.0.7\" -DAFL_CLANG_FLTO=\"-flto=full\" -DAFL_REAL_LD=\"/usr/bin/ld.lld\" -DAFL_CLANG_LDPATH=\"1\" -DAFL_CLANG_FUSELD=\"1\" -DCLANG_BIN=\"clang\" -DCLANGPP_BIN=\"clang++\" -DUSE_BINDIR=0 -Wno-unused-function -fdebug-prefix-map="/AFLplusplus=llvm_mode" -Wno-deprecated src/afl-ld-lto.c -o afl-ld-lto
src/afl-ld-lto.c:261:15: error: use of undeclared identifier 'PATH_MAX'
char thecwd[PATH_MAX];
^
1 error generated.
make[1]: *** [GNUmakefile.llvm:438: afl-ld-lto] Error 1
The issue is similar to #705, but happens on Alpine Linux.
The fix is also similar: include limits.h (#706).
Though I can't find the relevant macro definition to detect whether we're building on alpine.
Tested this on current dev (6e5ca0c)