JUCE: Fix build on musl

From https://github.com/juce-framework/JUCE/pull/1239.

Signed-off-by: Violet Purcell <vimproved@inventati.org>

source/modules/juce_core/juce_core.cpp

@@ -103,7 +103,7 @@
  #include <net/if.h>
  #include <sys/ioctl.h>
 
- #if ! (JUCE_ANDROID || JUCE_WASM)
+ #if ! (JUCE_ANDROID || JUCE_WASM || JUCE_MUSL)
   #include <execinfo.h>
  #endif
 #endif

source/modules/juce_core/native/juce_linux_SystemStats.cpp

@@ -198,22 +198,22 @@ String SystemStats::getComputerName()
 
 String SystemStats::getUserLanguage()
 {
-   #if JUCE_BSD
+   #if JUCE_GLIBC
+    return getLocaleValue (_NL_IDENTIFICATION_LANGUAGE);
+   #else
     if (auto langEnv = getenv ("LANG"))
         return String::fromUTF8 (langEnv).upToLastOccurrenceOf (".UTF-8", false, true);
 
     return {};
-   #else
-    return getLocaleValue (_NL_IDENTIFICATION_LANGUAGE);
    #endif
 }
 
 String SystemStats::getUserRegion()
 {
-   #if JUCE_BSD
-    return {};
-   #else
+   #if JUCE_GLIBC
     return getLocaleValue (_NL_IDENTIFICATION_TERRITORY);
+   #else
+    return {};
    #endif
 }
 

source/modules/juce_core/native/juce_posix_SharedCode.h

@@ -167,7 +167,7 @@ int juce_siginterrupt (int sig, int flag)
 //==============================================================================
 namespace
 {
-   #if JUCE_LINUX || (JUCE_IOS && ! __DARWIN_ONLY_64_BIT_INO_T) // (this iOS stuff is to avoid a simulator bug)
+   #if JUCE_GLIBC || (JUCE_IOS && ! __DARWIN_ONLY_64_BIT_INO_T) // (this iOS stuff is to avoid a simulator bug)
     using juce_statStruct = struct stat64;
     #define JUCE_STAT  stat64
    #else

source/modules/juce_core/system/juce_SystemStats.cpp

@@ -133,7 +133,7 @@ String SystemStats::getStackBacktrace()
 {
     String result;
 
-   #if JUCE_ANDROID || JUCE_MINGW || JUCE_WASM
+   #if JUCE_ANDROID || JUCE_MINGW || JUCE_WASM || JUCE_MUSL
     jassertfalse; // sorry, not implemented yet!
 
    #elif JUCE_WINDOWS

source/modules/juce_core/system/juce_TargetPlatform.h

@@ -33,6 +33,7 @@
     - Either JUCE_LITTLE_ENDIAN or JUCE_BIG_ENDIAN.
     - Either JUCE_INTEL or JUCE_ARM
     - Either JUCE_GCC or JUCE_CLANG or JUCE_MSVC
+    - Either JUCE_GLIBC or JUCE_MUSL will be defined on Linux depending on the system's libc implementation.
 */
 
 //==============================================================================
@@ -92,6 +93,14 @@
   #define JUCE_LITTLE_ENDIAN 1
 
   #define JUCE_INTEL 1
+
+  #if JUCE_LINUX
+    #ifdef __GLIBC__
+      #define JUCE_GLIBC 1
+    #else
+      #define JUCE_MUSL 1
+    #endif
+  #endif
 #endif
 
 //==============================================================================